It’s perfectly normal , when you serve notice , your monthly bill is already in production, ( the billing date and your minimum term expiration date are not necessarily aligned ) so you pay the full month , any days you have paid for after the notice period has ended are refunded usually by reverse direct debit ( if you pay by DD ) so it’s not a good idea to cancel the DD .
It is the way pretty much every provider deals with customers that leave , even those that give the appropriate amount of notice .
