Great question. I have always had coooperation from RCCL and HAL. Not so for Celebrity. We booked two cabins before 9/11 and while everyone was running away, we stayed loyal. They were miserable at the pier and would not upgrade the other party (my cousin.) We had a confirmation for a better room and upon arrival, they refused to honor same. As far as I am concerned, the travel agency handling this blew it.