I just received seven (7) letters from Delta on the same day, all pertaining to the gift cards. I keep very good records of all the gift cards I purchases thru AMEX Platinum. (3) of the gift cards were still valid, so I sent the (3) letters back with continue to maintain balance checked.
But, May 2021, I had used the remaining (4) gift cards letters referred to. Seriously, Delta does not even know I used the gift cards????
I still have the gift card numbers and redemption codes. Will not try to use them again, but it would serve Delta right if I did.
Delta not quite as "world class" as they like to think of themselves.