Sympathise totally. they are treating you very badly indeed.All this I do undestand BUT it is time for them to check on the accuracy of their algorithm! My account is NEVER in debit or in a neutral balance!! I am always at least £200 in CREDIT even AFTER they have taken their quarterly share!! Hence my indignation, which has now turned to rage, after receiving both emails and letters insinuating that my meter readings are 'inaccurate'. To add fuel to the fire, they then said that they would send an engineer to put me on a Smart meter. The account in still in credit to the tune of at least £380 after they have taken out an increased May monthly payment to start the new quarter.
As I said before, Octopus actually do listen and do modify your DD, so in the short term you could just switch to them, but if you want to have a go at your present supplier then I'd write them a letter stating what you think is unfair, making a formal complaint, and if they do nothing, take it to the Ombudsman. with your payment record, Octopus will welcome you with open arms, but you'll have to have a smart meter.
We don't have a problem with that, but then each case is different and we have a special reason for wanting one.