I recently cancelled a Delta ticket along with a travel companion certificate because of a change in plans. I originally used my AMEX Delta reserve card to make the reservation. The agent cancelled my ticket and I was told she was going to issue me a complete refund to my card and redeposit the companion ticket into my account for future use and also refund the taxes on that ticket. The refund for all charges were in my AMEX account 3 days later and the companion ticket was immediately available after I hung up. I'm sure AMEX is going to go after all the points deposited in my Delta account from these tickets which I fully expect for them to do. I'm very happy with how smoothly everything went.