Raise a written dispute with the old supplier today and ask for the bill to be put on hold while it is checked. If nothing is done, the account often gets chased as overdue and can be passed to debt collection even when the figures are still being argued. Keep paying any amount that is clearly correct (such as standing charges up to the switch date) so the dispute stays focused on the difference. Get the meter readings and switch dates in one place before any phone calls, then follow up in writing.
Most people see this after a switch has completed and the first “final” bill arrives, or after a partial response to a complaint that does not correct the balance. It can also appear when a supplier issues a revised final bill weeks later, often after a data update from the industry systems. The problem tends to hit tenants and new homeowners hardest because the move-in and move-out dates add another layer of readings and responsibility. It usually becomes urgent when a direct debit is increased, a refund is withheld, or a debt letter arrives despite earlier contact.
What the problem is
A final bill that looks wrong after switching energy supplier is usually a mismatch between what the customer believes was used up to the switch date and what the old supplier has billed. In UK switches, the closing meter reading is meant to be agreed between suppliers through the industry process, but customers often only see the end result as a single balance due or a surprise refund. The issue often shows up after a customer has already provided readings, or after being told the switch is complete and the old account is closed. It commonly appears after a complaint has been opened and the supplier replies with a generic explanation rather than a corrected bill.
Why this happens
The most common cause is an incorrect opening or closing reading being used, which then cascades into the final bill. That can happen when a customer submits a reading but it is rejected as “too high/low”, when an estimated reading is substituted, or when a smart meter has communication gaps and the supplier falls back to estimates. Another frequent cause is timing: the switch date used for billing may not match the date the customer thinks the supply moved, especially if there was a delayed registration or a change of tenancy around the same period. Credits and debits can also be applied late, such as an annual adjustment, a missed payment allocation, or a refund being held back while the account is flagged for review.
Suppliers have incentives to close accounts quickly and rely on automated data flows, so errors can persist until a customer forces a manual review with clear evidence. A typical organisational response pattern is a standard letter saying the reading came from “industry data” and the bill is correct, followed by silence unless the customer escalates through the formal complaints route.
One neutral, typical UK outcome is that the supplier reissues the final bill after the opening and closing readings are aligned between both suppliers.
Your rights in practice
The practical position is strongest when the dispute is narrowed to one or two checkable points: the agreed switch date, the closing reading used by the old supplier, and whether payments and credits were applied correctly. A supplier is more likely to act when the request is framed as a billing accuracy issue with supporting documents, rather than a general complaint about “being overcharged”. Asking for the account to be placed on hold during an active billing dispute often prevents avoidable collection activity while the figures are checked.
Keeping payments up to date for any undisputed amount usually helps, because it removes the supplier’s argument that the issue is simply non-payment. If the supplier claims the reading is “industry agreed”, the leverage is to ask for the exact reading and date used, and to request a rebill if that reading is inconsistent with the customer’s evidence or with the new supplier’s opening reading. Where the customer has moved home, the leverage improves when tenancy dates, completion dates, and move-in/move-out readings are clearly evidenced, because responsibility for usage is then easier to allocate.
Official basis in UK
The practical route for unresolved energy billing disputes is the Energy Ombudsman scheme, which can require the supplier to put things right, explain what happened, and correct bills where appropriate. In day-to-day cases, the scheme is used after the supplier has had a fair chance to resolve the complaint, or when the complaint has been deadlocked. The Ombudsman process works best when the customer can show they followed the supplier’s complaints process and can point to the specific mismatch (for example, the closing reading used by the old supplier does not match the opening reading used by the new supplier).
Before escalating, the supplier should be given the opportunity to investigate and issue a corrected final bill or a clear written deadlock response. The official route and the conditions for taking a complaint to the Ombudsman are set out on GOV.UK guidance.
Evidence that matters
The evidence that tends to resolve these disputes is simple and dated. The most persuasive items are the meter reading taken on the switch date (or as close as possible), the reading submitted to each supplier, and any confirmation showing the supply start/end dates. If a smart meter is involved, screenshots from the in-home display can help, but the key is the meter’s own register reading and the date it was taken. Bank statements or payment confirmations matter when the balance looks wrong because payments were not allocated, or when a refund is missing.
What not to do is keep phoning without a written trail, because the dispute often turns into “no record of that call” and the same explanation is repeated. Avoid sending original documents; send copies or screenshots. Do not alter photos of the meter reading beyond cropping, because edited images can be challenged and slow the review.
Common mistakes that delay fixes are: relying on a single undated photo with no context; disputing the whole bill without stating what figure is believed to be correct; cancelling the direct debit immediately and then ignoring letters while waiting for the supplier to “sort it out”.
Do not submit a complaint to an external body yet; the supplier’s formal complaints process needs to be used first so there is a clear record and outcome to escalate.
Quick checklist
- Photo of the meter reading with a visible date stamp or phone metadata
- Switch confirmation from the new supplier showing the supply start date
- Final bill showing the closing reading and the period billed
- Proof of payments and any promised refund amount
What to do next
Pin down dates
Write down the switch date shown by the new supplier and the final bill period shown by the old supplier. If they do not match, the first request is for the old supplier to confirm the exact supply end date they used and why. Where a home move overlaps, add the move-in or move-out date and the reading taken at handover, because that often explains why the account has been billed to the wrong person or for the wrong period.
Dispute in writing
Use the old supplier’s official complaints process (usually found under “Complaints” or “Make a complaint” on its website) and submit the dispute in writing so there is a reference number. Prepare the final bill number, the closing reading used, the reading believed to be correct with the date taken, and the new supplier’s opening reading if available. Ask for the account to be placed on hold while the billing accuracy issue is investigated, and ask for a corrected final bill or a written deadlock response.
Keep paying basics
If part of the bill is clearly correct, pay that amount and state in writing that the remainder is in dispute. This keeps the focus on the disputed units or dates rather than creating an avoidable arrears argument. If the supplier threatens collection while the dispute is active, repeat the request for a hold and keep all letters and emails together.
Check linked issues
If the supplier suggests withholding payment as leverage, it is usually safer to understand the risks first; the practical boundaries are similar to other household disputes, and Withholding rent — when it’s allowed explains the typical UK consequences when payments are stopped without a clear plan.
Escalate on silence
If there is no meaningful response, follow the supplier’s complaints escalation route (often “Stage 2” or “Manager review”) using the same reference number and attaching the earlier message. The normal response timeframe is that an initial complaint acknowledgement arrives quickly, but a proper billing investigation can take several weeks depending on reading disputes and data corrections. If the supplier issues a deadlock letter, or if the complaint has been open long enough without resolution, escalate to the Energy Ombudsman using the official route referenced in the GOV.UK link above and provide the evidence bundle already prepared.
The issue is usually resolved in UK cases when both suppliers’ readings are aligned and the old supplier reissues the final bill with a clear calculation.
Strategy shift
If the dispute is really about who is responsible for the supply (for example, the account is in the wrong name after a move), change the request from “rebill my usage” to “correct the account holder and liability dates” and provide tenancy or completion evidence. If the supplier keeps repeating that the reading is “industry agreed” without sharing the figure and date, ask specifically for the closing reading and the data source used, then ask for a formal deadlock response if they will not investigate further.
Related issues nearby
If the final bill dispute is happening at the same time as a move, it can overlap with other end-of-tenancy money problems, especially where a landlord or agent is holding funds back while bills are argued. In that situation, Tenancy deposit not returned after 10 days can be relevant once the tenancy has ended and the deposit is being delayed for “utility deductions”, and it helps to separate what is genuinely owed from what is being used as leverage.
FAQ and fixes
Opening reading mismatch
An opening meter reading mismatch after switching supplier is usually fixed by getting both suppliers to confirm the reading and date they hold and asking the old supplier to rebill to that agreed figure.
Debt letters arriving
Debt letters during an energy bill dispute often stop once the supplier is asked in writing to place the account on hold and the undisputed amount is paid.
Smart meter gaps
Smart meter communication gaps on a final bill are commonly handled by providing a dated photo of the meter register and asking for estimates to be replaced with that reading.
Refund not paid
A refund not paid after a final bill is usually released when the supplier confirms the account is closed, reallocates any misapplied payments, and issues a final statement showing the credit balance.
Before you move on
Keep the dispute narrow, keep it in writing, and keep the evidence dated so the supplier has something concrete to correct. Time pressure can show up as being pushed to accept a “goodwill” adjustment quickly instead of getting the readings and dates properly aligned.
Get help with the next step
Contact UKFixGuide — If the supplier is still chasing the balance while the final bill is disputed, include the bill number, the switch date, and the reading evidence so the next message can be drafted clearly.
