Being charged a "Non-returned receiver fee"...when I have no receiver to return

I moved back in December and was told to simply bring all of my equipment with me to my new address. You know the advertising made it seem so simple- "We make moving easy!". At my previous address we were paying for U-verse (3 tv receivers) and internet. We ended up ADDING a tv after the move. So to clarify, we are currently using 4 cable boxes and our internet router. I got an email at the end of January to return one of the wireless TV receivers...but we were using it (I checked the model and serial number in the email with the actual equipment being used in my room). I called shortly after receiving the email and was told it was simply and automated email and I would not be charged. Lo and behold on March 6th I get another email that my bill is ready to be viewed and what is on it? A $171.00 charge for a non-returned receiver. I called AGAIN to ATT on March 6th and spoke with a lady named Sunshine and expressed my frustration. She said the issue would have to be sent to the back office team and my bill should be fixed in 5-7 business days. Already weary the situation would not be fixed I asked if she could call me back personally to follow up. 10 days later and no fixed bill or call back from ATT. I then thought maybe the online chat option would work better. So March 16th I chat with Wesley about the issue and he says the "back office is taking care of it" and extends my due date on my bill. The next day, I was officially over this game and decide to call back AGAIN. This ATT rep tells me he sees NO RECORD of me disputing the charges. I REPEAT NO RECORD. So I go through the whole explanation of my situation AGAIN. I asked for him to send me a copy of our phone conversation to my personal email-which I never received. It is now 2 weeks later and my bill is still not fixed. For the sake of my sanity someone help me.