I'm incredulous on your behalf, cutup
I was a teenage musician myself, and I remember there being a whole lot of competition between different areas of study - I was also into sports and I often felt like I was being pulled in several directions with different subject leaders vying for my time, not by offering incentives but by punishment when I couldn't fulfil every obligation.
Anyway, that explains why I'm cross on your behalf.
That's a huge amount of money to lose considering they are the ones that have made the decision to cut her out of the trip. It sounds horribly like it's too late to get her back on the trip now but I would be thinking about taking it much further in an attempt to get the money back somehow. Embarrass them in the local press, maybe?
Does she go to a specialist music college (cheetham maybe?) The musical directors of youth orchestras are often jumped little wannabes who get very precious about the commitment of the players, in my experience but I guess you know that already
Best of luck, and I sympathise greatly with your daughter. A musical director (of an out of school orchestra) managed to get me expelled from my school for non compliance to his ridiculous rules whilst on tour. Arsehole.