UW - Refused to pay me back my accumulated credit from Energy bills to my bank account

Scot_39

It is not unexpected that suppliers expect a small credit balance over summer on an annualised DD plan.

Rather than neutral and catching up with a loss over winter vs DD rate the next summer - a bad cash flow scenario for any business in a 5% interest environment.

Without full details of the credit level against standard DD and OPs winter to summer bill costs etc. It is impossible to say whether OPs credit excessive or not - and worthy of refund.

People get very upset about the concept - but a company providing credit will charge for it.  Just as standard credit terms are now the most expensive.

And Ofgem thought it was a significant enough cost to consumers not to ring-fence credit balances.

If unhappy with fixed DD and its credit balance cycle  - switch to a supplier who offers monthly variable DD at DD rates. If that is you are either disciplined enough to hold the reserves in a savings account yourself over summer to pay higher winter bills or simply can afford the higher winter bills anyway.
Or a supplier who will refund more willingly and allow more flexibility on DD as long as monthly bills paid by DD or card etc as due - like some here have said about Octopus and setting DD manually in a wide range.