When you moved to BT TV did you ask BT to move your old NOW account and Memberships across to BT ?
If not or you was using two different NOW accounts then this could be the reason why you are still billed by NOW.
TV customers can use the NOW live web chat service, where there is a real person on the end of the web chat, but unfortunately this is done by typing in real time, rather than speaking to somebody over the telephone.
NOW don't have a telephone helpline for their TV Membership customers (only Broadband customers).
Use the link below to click on the green chat online button or alternatively send them a message using the web form (also on the same link).