iPhone 13 Pro sent to T Mobile facility and IME number has not been verified as recieved

Upgraded to iPhone 15 Pro.  Per t-moblie I used provided return label and sent iPhone 13 Pro to t-mobile facility in Texas.  USPS tracking number verifies delivery has been made but the IME number of the phone as not been scanned in, or recognized as received by t-mobile.  It has now been 4 weeks since the phone was sent to t-mobile to receive credit.  The first t-mobile customer representative claimed I sent the box and did not place the iPhone 13 in the box. He also claimed someone may have opened the box in transit, removed phone, resealed box and sent it on to t-mobile?!  Maybe someone at the t-mobile facility in Texas stole the box after it was recieved.

1. I would like the credit promised by t-mobile ($350) for the phone I returned per t-mobile instructions and t-mobile provided label.
2. Don’t like the implication I purposely deceived, lied to t-mobile about returning the phone.  Second t-mobile customer representative was less accusatory and verified the IME number is not active.
3. I have documentation USPS delivered to Texas t-mobile facility with time, date.

Recommendation, t-mobile should always recommend customer to return phone to physical store.