We are fellow users and other than the Apple hosting team, Apple is not here, and no one can process your request for a replacement trade-in box. Contact Apple in your country and ask for a replacement trade-in box.
I had a situation in October where no trade-in box arrived, though FedEx showed it initially lost then claimed delivery when it was not delivered, and then sent me an email indicating they found the box in Pakistan. I called Apple and eventually was connected to the person that could resend a trade-in box — which was successful.
I did not retain any information from the second paragraph in regards to contacting/who at Apple helped.