Att universe home and internet

I cancelled my service back in October and att only cancelled my telephone line. They didn't cancel my tv nor my internet. Att continued to withdraw money account. I have been trying to resolve this since may. Att has continued to telll me that the matter has been escalated and someone is working on it. It's been 2 months and I've been calling almost everyday to hear the same thing. Att owes me $1200. That was never to be taken from my account. Att has been unresponsive and they've been sending to different people. Even when I speak to managers they assure me that they will be fixing this problem and they will themselves call me back. And still today I'm waiting for phone calls and my credit. In can't believe that such a big company can cheat and steal from customers...