Equipment charges & missing trade in

I was promised by “in home expert” who sold me AT&T phone service that my phones were free. I traded in my existing iPhone . I have been charged equipment fees since day one & AT&T says they have no record of a trade in from me. After a month of me contacting AT& T about this they said, not their problem, rep who signed me up is contractor & his company must have had a promotion so it is my responsibility to get THEM to honor that promotion & notify AT&T of my trade in as well. Supervisor with contract company says he will look into it. Now will not return my calls! So shady!