Still getting charged two months after activation

Hey guys!

So I cancelled my phone and transferred the number to my new service provider (I moved and AT&T did nt have service in central Washington). Balance was 0.00

Got charged three or four weeks later. Went in, was told it was (another) cancellation fee. Balance was at 0.00

Get charged again four days ago. Was again told it was "the cancellation fee". This was the manager, after the first two employees kept staring at their iPad (Galaxy?) and telling me they had no idea what was wrong and they had never seen anything like it before.

I've been told twice I've been cancelled, had a balance due of 0.00 three times, and been charged $120-140 for two straight months despite having a cancelled contract and recycled the phone.

What do I have to do to have my contract finally cancelled and go about being credited/refunded the arbitrary payments?