It always takes a while as you paid in advance and the billing cycle simply continues on the normal dates to show exactly how much you are in credit by, and a subsequent bill confirming £0.00 balance.
You can claim back the surplus via My Account, using the bank details still in place.
If you stop the Direct Debit too soon, a cheque can be issued, but it's less efficient, @kkkev11.
Gliwmaeden2, a fellow customer.
