Did you bring your Pgen account with you to this address?
At least they have offered to resolve this issue with you for you overpayments.
Those electric wall heaters cost a fortune to run and only work if your at home all day long, even on E7 tarrifs they worked out badly effective for warmth vs costs(for me).
How did you buy somewhere that you couldnt get access to your meters?
Seems a half and half situation because one of the first jobs when one moves into a new place is to get meter readings and send them into the supplier.
I hope you have some luck resolving your overpayments, Pgen are a fairly decent supplier in that area and should issue you a refund providing your consumption has deacreased accordingly
