Apple keeps losing my trade ins…

For the 2nd time, for the second iPhone trade in, I’ve received an email from apple stating my trade in was canceled and I will be charged… I’ve spent WAY TOO much time on these issues talking to customer service on the phone, via text and chat, and they still can’t figure this out. Provided BOTH times, photos of tracking numbers, the fed ex box drop off location and the fed ex tracking receipt showing THEY received them. Why does this keep happening and how do I resolve this?