Once I had to rebook an island to ATH flight in business class to later in the same day after I had missed my flight because the hotel failed to do my wake up call. My ticket was part of a TATL complex trip, not on A3 stock and ticketed by AmEx. When I reached my TA by phone, she was able to make the changes instantly and efficiently, at no additional fare. Check in at the airport was efficient and drama free, with no additional time needed. Except for the hotel, it was a good experience.