Legal Question in Consumer Law in North Carolina

I don't know and would have to see your bill. Look at what the bills says is the term or period of service. It may be that they are a month behind and that the bill you received is for service for the previous month prior to your termination. It may also be that you had some kind of contract. If so, read the contract or terms of service. Whatever those say will govern and you agreed to it when you signed up for the service. If you are still stuck, then call someone in their department and try to speak to someone in authority at the company (not in a call center in India) who knows the answer.

If it turns out they are still charging a junk fee for no service, then file a complaint with the PUC (public utility commission) or whatever governmental agency regulates the company. Also, complain to the NC Attorney general if nothing else works.