I presume you are running Disney+ on a NowTV Stick, otherwise Now wouldn’t come into it?
if so, try holding down the little button on the side of the Stick for five seconds, while it is powered on, until it soft reboots. (Take care not to hold the button down for fifteen seconds, or it will hard reset, which you probably don’t want).
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.