Some time ago I, my wife and a friend booked tickets with Bmi to go to Cairo in May. Unfortunately, the people we arranged to stay with have had to move suddenly. This negates much of the reason for our visit but rather than cancel, we thought we would go somewhere else in the world in that week. I have spoken to three representatives of Bmi today who have told me that I can book a different plane on a different day at a different time in a different month but it must be one going to Cairo! When I asked for a reason why, not one of them was able to give me a reason merely stating that it was the rule. In fact it is perfectly possible that our new destination would involve a more expensive ticket. In my experience, rules that have no justification are either silly or sinister but I feel that all people who book early through airlines should be aware of Bmi's 'rule'.