I had sent my old device iPhone 6 Plus to Tmobile for a trade in credit. The tracking # showed Tmobile warehouse already received it but no credit was issued. I have been contacted customer service so many times and they said they didn't receive the

The 1st investigate result they email me. After that i contact customer service and they investigate again and told me over the phone. Do you know anyway can help me. i have filed a claim with UPS but maximum amount they mite cover is only $100 and of course my phone cost more than that. Ill be very appreciated if you can help me solve this issue.