Welcome to the forum.
If you don't see any active passes when you go to your My Account > My Passes page
and you don't see any charges on your bills page
then the charges will be coming from a different account.
Might be worth checking you haven't got any old NOW TV accounts, it often happens that people set up more than one account to take advantage of different promotions and explains why they keep getting payments made even when they seem to have cancelled everything. The following help page will explain how to track down other accounts.
If you still can't find where the payments are coming from have a word with Live Chat they can help you track down where the problem is. To get to live chat go here
and N dclick the Start Live Chat button.