Returned equipment charge

I returned my Directv equipment 12/19/2023 to the UPS store as directed by AT&T and Directv. I have the return reference number, serial numbers of equipment, and my receipt. I am being threatened by Directv with collections for $144.45 for unreturned equipment. This has been going on for almost 6 months. I have had numerous phone calls and yet they keep telling me I have to pay the unreturned equipment fee. Now today they are telling me the equipment was defective but yet they can't provide any proof that said equipment was ever checked in. I am being harrassed and threatened over equipment from 2014. The equipment was in working order when I checked it in at the UPS store. This treatment of a former customer is horrendous and to try and insist that I have to pay for equipment that I have proof I returned is insulting.