being charge for a FREE tablet

i went to an att kiosk on may 15th 2015.  i told them i wanted a tablet.  they said if you get a samsung s6 you would get a free samsung tablet.  i had to give up my iphone to do it.  6 months later i see on my bill that they have been charging me a monthly installment for my FREE tablet.  i chatted with someone online and they  made a case and looked into it admitting that it was a mistake and it should be free.  a month later there is still another charge on the free tablet.  i call and they tell me the case was closed and not only will not refund the money they fraudulently took but the will keep taking money.  they deny there ever was a free tablet.  finally i talk to a manager and she was all nice and understanding and said she would look into it.  tonight i look at my bill and i was charged 209.99 (the remaining balance on my free tablet) all at once AND it was past due.  

i talked to a manager and he said there is no such thing as a free tablet.  the manager i talked to lied to me to get me off the phone.

i am beyond *** right now.  att is not getting a single *** dime from me.  they can take it to a collection agency.  if i ever find proof that i was promised a free tablet i will [Per Guidelines:  Keep it Relevant and Appropriate].