From here, you can contact Now via Live Chat.
Or for Broadband customers only with Broadband-related issues only, via telephone.
Avoid ‘Get Help Quickly’ on this screen. This leads to the Nowbot, an AI bot that would assist you in navigating the Help very nicely; but you are already beyond that.
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.