I had the same problem and I solved it by numerous e-mails, photos of the box, proof of purchase. Took about 3 weeks and it was obvious that each agent hadn't read the previous e-mail history, so I was going in circles for quite a while. I'll try and remember to use the App in future then, thanks.
Z690 Hero, 12900K, BIOS 4001, MEI 2433.6.3.0, ME Firmware 16.1.35.2557, 7000X Case, RM1000x PSU, ASUS TUF OC 3090TI, 2 x 16GB Corsair RAM @ 5200MHz, Windows 11 Pro 23H2, Corsair H150i Elite AIO, 4x Corsair RGB fans, 3x M.2 NVME drives, 2x SATA SSDs, 2x SATA HDs.