I am not a lawyer, but...
If money has changed hands, you will likely be in a contract. But you'll probably find that, in the terms and conditions, the airline reserves the right to terminate it. In that case of a discount ticket, you don't have the right. That's the way it goes.
It's worth pursuing to see if you can get something from goodwill (it's not as if you were getting a $0.01 fare or anything), but I doubt you'd have any legal recourse.
[This message has been edited by stut (edited 10-21-2003).]