You should keep your money set aside for your expenses. The bill will come due when the other party figures out they have been paying your card off. Not sure how this happened honestly, a bit strange. You should double check someone else doesn't have access to your account because I am sure this can easily turn against you.

What does it say on the payment line? Does it mention where the money is coming from? Mine says that it is coming from my bank account and shows the last 4 of my account number.