My 2 Cents

I read an article on Yahoo news approximately 6 months ago talking about AT&T. It is similar situation that the client moved to an area that the service is no longer stable. She is able to have AT&T cancel her contract without paying penalty.

Your situation, I guess the operator made a procedure mistake. Instead of opening a shield account and transfer your existing contract to this account, she might cancelled your contract and opened a new one. The outcome is the same and because of the procedure is wrong, you are going to pay a fee. I would try to talk to a supervisor or go to a AT&T store (not private owned store) and talk to real person. It is not a big deal just explain the things clearly and you should be fine.

I used to be a front desk manager, we had similar situation when the guests want to change a room during their stay.