Xfinity Mobile Trade-In issues

We purchased two iPhone 17's on 6/30/2026 and as part of the transaction we took advantage of a trade-in promotion for our old iPhones. We shipped both phones on the same day (7/11/2026), but only one phone was processed. We were told we had to use the Xfinity Mobile provided shipping labels and had to ship the phone separately. During multiple phone calls we were assured by Xfinity Mobile staff to "Not worry about it" and that everything would be ok and the credits will be processed and we would get the credits. We have called Xfinity Mobile nine times and spent over six hours on the phone. The instructions we're given to rectify this issue keep changing and Xfinity Mobile isn't being responsive. They have promised calls from Supervisors that never happen. We were told to contact Assurant, but the only number they have provided is an automated number. Since the one phone did not get delivered to Assurant, it is not in their system and we are disconnected after entering our information. We've filed complaints with the USPS, but the search for the missing mail does not have any status updates after 2-plus weeks.

How has anyone else dealt with this issue with success? Can anyone from Xfinity Mobile actually assist with this?