He got 2x cat 5 certs promo for Spring Megabonus and since he was running his Plat challenge, he asked MR to swap his promo from 2x cat 5 to 3x cat 4 and it was accepted.

He got an email from them saying that he can just reply the email and have the certs swapped. He did and he was told that his cat 4 certs will be available within 48 hours. I haven't checked his account and I do trust Marriott that they will be there. If not, I'll write to them again.