Upgrade at airport - availability but no seat
2-Hours before departure Expertflyer showed availability in various Business booking classes, including O-class. I wanted to use this seat to upgrade my U-fare back to AMS.
At the airport ticket office they told me I couldn't upgrade because the flight was full. On the monitor they showed me 29 seats booked, 30 seats taken.
Can some one explain why upgrade availability is shown when there is no seat available? J/C booking class I can understand but O-class not.