The energy supplier overcharged you. Again.

Your energy bill is wrong again and you've got the meter readings to prove it. This drafts a complaint to your supplier, cites Ofgem's back-billing rule that bars chasing debt for energy used over twelve months ago when they billed badly, and demands a corrected bill within ten working days or it goes to the Energy Ombudsman.

Draft a complaint to [energy supplier] disputing a bill of [amount] covering [period]. My actual meter readings for this period were [readings]. Cite Ofgem's back-billing rule: suppliers cannot recover debt for energy used more than 12 months ago if they failed to bill accurately. Demand a corrected bill within 10 working days or I will refer the matter to the Energy Ombudsman.