How much does it cost to call 0330 numbers? I can't find an answer anywhere online because NOW TV have changed their name to NOW for some ridiculous reason. Searching for the word now the is ridiculous ans seems to be deliberately obfuscating.
Set a Payment PIN on your account so that no-one but you can buy memberships on it. Check your bank accounts monthly for any other unexpected payments to Now. That way you can at least nip them in the bud, while you and Now figure out whose fault they are.