Best answer by woz
ahhh I see what you're asking now and there are two separate things going on here.
Your annual is split into 6 winter and 6 summer payments.(60% paid in colder months, 40% in warmer)
Your balance should hover around a month's average payment when the dd is paid. If it's constantly increasing or decreasing you can have it reviewed at any time (PP look at it every 6 months)
If you want a review because you think you've built up too much credit (don't forget to deduct a months payment from your balance) just go to help, ask wattbot, type message the team and ask. PP will review and agree a new payment with you. You'll only ever pay for the energy you use.
But why should the direct debits go up if there is a large credit balance on the account. So, how do I request PP to review the account?