I think I’m going to raise complaint because like you I had an initial chat agent who confirmed I’d met the spend target prior to the change and would be issued the voucher in a few days. Then when I followed up a week later I was told the first agent was incorrect and because the transactions on the 29th weren’t fully processed by Amex until 1 Nov they apparently count that as being spent on 1 Nov and not 29 Oct when the transaction actually occurred.

This experience has confirmed my decision to cancel or downgrade the card as it’s not worth the increased fee, especially if Amex customer service standards have also dropped.