How to escalate issue to upper management for Trade In promotion ?

Ugh I need to read these forums before I'm a suxker for this scams or promotions. I have been a tmobile cx for over 9yrs and before that sprint for another 10. I got sucked into this promotion and got approved by upper managerment tech lady who sold me gave me their personal guarantee but I've heard that before. I traded in 3 devices one insurance phone to assurant who I believe never scanned in and gave directly to tmobile for my promotion. So I do believe tmobile ended up with all 3 and assurant didn't scan it in after they recieved it. I got charged a fee for non return I called this way back months ago and said this will happen and sure enough. Lost phone, no the right promotion. Nothing but empty promises and csr after csr on both assurant and tmobile. The only solution or how to getba respond ive heard is contact FCC and the BBB so I will do this after the holiday enough is enough. It seems this is ongoing and I believe with my loyalty as a cx I shouldn't be treated like this. I pay for 4 phones and scummy insurance I guess and upgrade every other year full price never no complaints. This has been a Rollercoaster the last few months.