They Refuse to Cancel My Service and Still Bill Me.

I called to cancel my service over a month ago, I was told they would submit everything and then send me a final bill. Then a couple weeks later they started calling me 3-5 times a day! I had a hard time answering since I work during the day and was working when they would call. When I did finally speak with them I was told I needed to resolve my balance in order to reactivate my service as it was suspended. I told them my service was supposed to be canceled and I was supposed to receive a final bill. I was then told that they would not cancel my service until the past due balance was paid. When I told them that I had not been informed of this when I called in to cancel my service in the first place and wanted to know why I had not been told this in the first place the representative became rude and would talk over me. I finally got off the phone with them and have now noticed that my service has not been canceled and continues to be billed and they are calling me 3-5 times a day threatening to send me to collections. But they refuse to cancel my service and send me a final bill.