FedEx Lost my iUP trade-in device?

Title. My iPhone 12 Pro has been allegedly been under inspection of the trade-in facility for over 2 weeks, and it actually apparently failed, showing that I need to still send it in (they sent me another trade-in kit)-- This led to Apple continuing this loan on the previous phone on top of the new phone. Keep in mind, I traded my phone in via FedEx shipping with the box provided, not a physical hand-in at an Apple store.

One of the representatives told me that the FedEx facility reported my box contained NO phone at all, despite that not being the case. With that in mind, the representative brought this case into further investigation with the iUP specialists, as my situation has happened before in the past. With that being said, I've contacted Apple support 3 separate times now, but I've gotten nothing back in Orders or Emails after chatting to them. How can I contact a supervisor, leader, or even an Apple store in-person to get this figured out?