They’ve done the same thing to me on multiple accounts over the past few months. Closing the count after using gift cards. They ask to verify the cards I send them pictures of gift card being received to my email and they say sorry not enough information. I’ve lost thousands of dollars from them. I’m thinking of suing in a small claims court
I had similar, where even after I emailed them proof of purchase they wouldn't reply to me...
But even though the email said the GCs were being "confiscated", the balance was still there on my amazon account and I was able to use them. I would check your account GC balance.
I actually contacted a few law firms about a class action lawsuit (Amazon invalidating GC illegally is nothing new. Just google it and read some of the reddit forums...), but all of them said this isn't their area of expertise, although one of them said I definitely have a good case...
I forgot about it after a bit.
If you want to get something going, I'm all in.