AT&T makes a mistake, admits it, then charges me for 3 months!

I sold my business in August and called to cancel my business phone lines on August 8th.  I was told everything was taken care of and it should be shut off in 7-10 days.  I received a bill in September, so thinking this might be an error, I wrote a letter saying the business was closed, and the phone lines were supposed to be cut off on August 8th.  I receive another bill in October, so finally, I call them up and ask what happened.  The woman who answered told me that she will discontinue the service.  I said that it was supposed to have been done in August.  She said, "oh, I see here that you did call, and this is our mistake."  Then she says I will have to pay the termination fee for my contract.  I asked how much, and for the remainder of the period it would be $100 but I still have to pay the three months of Aug, Sept and Oct since my termination is now Nov. 4th.  I said, "even if it is your fault?"  She said, "yes, it is our fault, but that is all I can do."  So I offer to pay the termination fee from August which is about $175 or so and she said she will send this to the credit dept.  Today I receive a bill for over $500 since they terminated the service on Nov. 4th.

Not only did I have my business service with AT&T, but I also have my home service with them.  I will definitely rethink this situation and possibly transfer my home service and open my new business with someone else.  For some reason, I am not shocked by how this was handled.