My AT&T trade-in phone lost/possible stolen

I brought my phone to trade in back in December 2023 from a iPhone 12 pro max to an iPhone 15 pro. I brought it to a physical store where they let me know everything is all set to go. When asked about when I would receive my credits, they repeatedly told me to not worry and the credit would should up on my account. When my trade in status online did not show up as "received -> completed", I asked them once more and they told me to wait 3 billing cycles later. When asked about a copy of my trade-in receipt, they gave me a shady one with the serial number crossed out, the wrong device to be traded in, and just overall terrible. After asking why the receipt was incorrect, they told me to not worry and it was ok on their end. Unfortunately, I made a little blip of not asking for the receipt then and there but never in my entire 10 year lifespan of being a AT&T customer was this ever a problem. Fast forward, I've been in constant contact with AT&T customer service to try and get this resolved and constantly calling the store itself to make sure my phone is received. AT&T customer service tells me during every conversation that I should be receiving the credits the next billing cycle and what do you know, it's not there! Any time I get it escalated to a manager, they just tell me to visit the store. Another bit of unfortunate events is that I was on vacation when I did this trade in so I do not live close to the store. Today when I called the actual store, they let me know they can't find the serial number of my phone anywhere in their system and it may have been stolen.

Not to mention... the person helping me out at the store was very creepy, kept trying to pursue me and flirt.....

This has been an extreme nightmare and I just want my credits back with no trouble. I already filed with BBB but anyone have advice on what else I can do?