Here are the dates of the various NowTV hardware releases.
If you have a Stick, it will be from 2018, not 2013.
If you have a device from 2013, it will be the White box, which is no longer operable.
Could this explain what you are reporting here?
Now TV "White" Box
Now TV "Black" Box
Now TV Smart Box (1st Generation)
Now TV Smart Stick
Now TV Smart
Box (2nd Gen)
|Release Date||July 2013||August 2015||July 2016||February 2018||September 2018|
|End of Support||October 2020||N/A||N/A||N/A||N/A|
|UK Model Numbers||2400SK||4200SK; 4201UK||4500SK||3801||4631UK|
| || || || || || |
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.