Look for a label on or under your router, on which the default SSID and password are usually given, and use that. These details are usually specific to your individual router.
If you have changed these details though, and forgotten what you have changed them to, then you will need to factory reset your router, after which you can use the values on the label to get going again.
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.