[RougeUnderoos]

Stall, and look for another job. I had an employer do this kind of thing to me (sort of, he just reneged on the salary structure on the contract and said "things change"). I handed in my resignation the next day and he about had a fit. Spit flying, fist pounding and the whole charade. It was very satisfying.

Oh yeah, and to answer your question with nothing but my own opinion, fighting them on it would be a big hassle and maybe not worth your time, especially if you stay there. If you get another gig elsewhere then maybe try to do something, but you won't have a lot of fun working there while fighting it.