I had the same problem when applying for my buds with my S21 Ultra chappy1011 in that they did not recognise my IMEI1 number but when I tried again with my IMEI2 number everything went through fine and my buds arrived some 40 days later.. 👍
Sorry to hear that chappy1011. Have you tried contacting whoever sold you the phone to see if they can offer any assistance, or ring the claims department up personally if there is a contact number there?.. 👍