i have just had the 15k service on my my99 and the front discs need changing due to cracks on the outside face only. has any one experienced this problem as the dealer says that the discs should do 30k? (give the dealer his due, he is doing his best to replace the discs under warranty.
i do a lot of varied driving but do not consider that i have a heavy braking foot.

I have heard of a few cases with these discs being cracked and replaced under warranty, so you are far from alone.