I had an *A F award ticket a European vacation this summer and wound up having to cancel due to my wife now needing medical treatment. There had been a schedule change of about 45 minutes on the final return (causing a longer connection time in SFO) leg that had happened some months ago but I never acknowledged. When I called to cancel, at first they were going to charge the redeposit fee, but when I mentioned the schedule change, they waived the fee. Never mentioned my wifes medical need.

For the same trip had an F award on US, and they were not willing to waive the redeposit fee. However, they never charged the fee to my credit card.

Bottom line is that you never know what they will do.