We are all customers like you here. So you’ll need to do the checking yourself.
Did you get an email confirmation about the cancellation? As it’s a lengthy process and if you didn’t get email confirmation then it’s unlikely to have went through.
Contact staff using the method provided by @redchiz1 then put a payment PIN on your account to be sure it won’t start without your say so.
FYI that I do not work for NOW, just a NOW customer trying to help