why was my trade-in cancelled?

Bought a new iPhone 17 pro and opted to trade-in my Samsung S23. Received my new phone and trade-in shipping label and box. I sent the trade-in back and a few days later I get a message that it's not what I said it was, and that they were shipping it back to me. So what do I do now? I gave the phone's IMEI number when I purchased my new phone yet somehow this isn't the phone I said it was? Interestingly, it looks like the box I sent it back in was never opened. What are my options now?