Best answer by Transparent
OK, I can help some more. I understand the maths, and OVO have handled this according to Ofgem guidelines. Please allow me to explain:
An Energy Account is different to a "credit account" such as you might have with a builder's merchant. An Energy Company may not operate as a bank, where customer debts lie on its balance sheet until they are paid-off in arrears.
(And equally, Ofgem will only permit OVO to pay interest on the first £1000 of customer account credit, for the same reason. It cannot and must not operate as a financial institution!)
At this time of year energy use is increasing. The general guideline is that Pay-Monthly (Direct Debit) customers should now have one month's DD amount of credit on their account.
So if your account is in credit to £330 and your DD is currently £150, then they have refunded you the remaining £180. This leaves the account with one month's DD amount in credit, as per the guidelines.
There are other factors in play, but I'd need to know more about your account to explain these. It would help me if you filled out your Forum Profile page. This will help me to see the type of deal you've signed up for and when is the renewal date.
Please remember, I'm just a fellow customer. I don't have access to any of your account data within OVO!