Energy bills are confusing — and when they are wrong, the amounts can be frightening. If you have been overcharged, hit with an unexpected back-bill, or cannot get a billing error fixed, you have clear complaint routes in the UK.
This guide explains how to make an energy bill complaint, when suppliers must refund you, and how to escalate to the Energy Ombudsman.
Common Billing Problems
- Estimated bills that do not match actual usage
- Wrong meter readings — yours or theirs
- Duplicate charges or tariff errors
- Back-bills for periods over 12 months (often not allowed)
- Failed to apply a credit or promised refund
- Switching errors between suppliers
Back-Billing Rules — 12-Month Limit
Ofgem's back-billing rules mean suppliers usually cannot charge you for energy used more than 12 months ago if the delay was not your fault — for example, if they failed to bill you correctly.
If you receive a large back-bill going back years, challenge it immediately.
Step-by-Step: Energy Bill Complaint
- Check your meter — take a photo of the reading and compare to your bill.
- Gather bills — last 12 months, tariff details, and correspondence.
- Complain to your supplier — phone first if urgent, then confirm in writing.
- Use their complaints procedure — suppliers must resolve within 8 weeks.
- Escalate to Energy Ombudsman — free, independent, if unresolved after 8 weeks or if they issue a deadlock letter.
| Problem | Likely outcome |
|---|---|
| Supplier overcharged due to wrong reading | Corrected bill + refund or credit |
| Back-bill over 12 months (not your fault) | Reduction or write-off |
| Billing delay on their side | Negotiated payment plan or refund |
| Switching error | Refund from responsible supplier |
Keep a dated record of meter readings and every call — suppliers often dispute timelines
What to Put in Your Complaint Letter
- Account number and supply address
- Which bills are wrong and why
- Your meter readings with dates (photos help)
- The refund or correction you want
- Reference to back-billing rules if applicable
- 14-day response deadline
A structured complaint letter speeds up supplier complaints teams
Energy Ombudsman
If your supplier does not resolve the complaint within 8 weeks, or sends a deadlock letter, you can go to the Energy Ombudsman free of charge.
They can order:
- A refund
- A bill correction
- An apology
- Compensation for distress and inconvenience (in some cases)
Direct Debit Overpayments
If you are in credit, you can usually request a refund of surplus credit — suppliers must refund reasonable credit balances when asked. If they refuse without justification, complain formally.
Using Refundly for Utility Disputes
Refundly covers utilities and telecom billing issues:
- Select "Utilities & telecom"
- See your complaint rights and ombudsman route
- Build a timeline with meter readings and bill dates
- Generate a formal complaint letter
Final Tip
Submit meter readings monthly through your supplier's app or website. Accurate ongoing readings are your best defence against surprise back-bills and estimated bill shocks.