I'll second both Val & Ben's advice. Tagging on a bit to Ben's - chances are you are not the only parent who is upset about this - I'd try to get a group together and present your concerns to the school board - this has actually worked to prevent cuts in our school district's gifted program.
I'd also be sure I had as much background info as possible - why were the cuts made (I'm guessing it's budget, not just block schedules), what are the perceived (or advertised) benefits to eliminating the challenge classes, and how will gifted students' needs specifically be met.
Good luck!
polarbear
