We're currently £240 in credit, which although not a lot, I think it could be spread to cover the "worst months" and reduce my DD. I was paying £190 in the summer months (4), so I was probably overpaying by £60 pcm. My tariff hasn't changed BTW, last month the DD was £120! They're adjusting to £165, so if I suggest to pay £120, I'm thinking my credit should cover the worst months. At least I can reassess next month and see how much of my credit I used. Is that such a crazy idea?