returning traded in phone

In March 2020, I upgraded my iPhone 8 to an iPhone 11 Pro (at a Sam's Club contract store) during the period that I was required to return my iPhone 8 to AT&T. The representative at Sam's Club said that AT&T would send me a package to return my iPhone 8 to them in the mail. To date, I have not received anything to return the 8 to AT&T and I have contact AT&T twice requesting the packaging to return it. All I have received is automated messages from AT&

T that the deadline to return my 8 is rapidly approaching and I need to return it or be charged the balance of the contract. One AT&T rep I actually talked to on the phone (Which is really hard to do during the COVID-19 Stay at Home period) said I could take it to the open store in the area and return it. I contact the store open in the area and was told by a sales rep and a manager that they can't do that, I would have to mail it in. I have been an AT&T Wireless customer since the days of Pac Bell Cellular and have never experience a problem like this. I want to return the 8 in accordance with the contract, but it seems no one can get me the return package to do it. What is the solution??????