Promotional Trade-In Credit Never Applied to Account?

What a scam… wish i read this sooner...on Sept, 2021 I went to my local T-mobile store looking to switch over from sprint to t-mobile and in the process i was offered a promotion deal to trade-in/upgrade for my phone. I had an iphone 8 256 gb.  After talking to one of the employees about their current deals, they employee suggested i sign up for the Magenta MAX and I would get a $800 trade-in credit towards an Iphone mini 12. i really wasn't interested in trading because i was happy with my iphone 8 and had 256 gb but was told if i didn't switch it would cause issues with the new service etc.etc. so reluctantly i traded in my phone under the condition that the trade in value would cover the cost of the new phone. low and below countless hours on the phone with customer service and 17 months later still paying $22.08 for the iphone mini12.. this scam is so convoluted that the customer service reps do not even know how to explain or handle the questions although one did say that there's was something wrong with the phone i traded in .. so i asked why wasn't i contacted and why wasnt the phone returned if it wasn't suitable to trade in then proceeded to tell me to contact the store where i purchased the phone. I did contact the salesperson and she was surprised at what had occurred and at that time i was on the plan for 4 months so she refunded $120 via gift card (at that time i was being charged $30/ month for iphone 12 mini)... (not sure why now im being charged $22.08/month) and told me she would attempt to get it straighten out but to date issue has not been resolved. Again where is my phone?? why wasn't it returned ?? why didn't i get the credit that was promised?? all questions still awaiting responses.

deceitful practice and untrustworthy company never had these issues with Verizon or sprint

very dissatisfied soon to be ex customer