I moved to where I have this account in September 2018. I get monthly bills for gas and electric and always show in debit. I recall in Feb 2019 I got a small refund. However now I'm nearly £600 in credit!
I've been informed they are going to back bill this but I've had no contact now since beginning of march and I domt want to keep paying if I'm in credit because I'm also being made redundant.