gm cadillac - duplessis won't honor gm warranty on a 08 cadillac cts / brake rotors cracked 31,000 miles baton rouge Louisiana

warranty booklet in my 2008 cadillac cts saids bumper to bumper warranty 50,000 miles or 4 years . what is not covered brake pads / linings/coolants/and fluids/and filters .on 11-28-09 I looked @ rotors thru wheels and saw cracks in the two front rotors .I called the dealership 'duplessis' and talk to service advisor 'todd suprun' he said he has never seen cracked rotors  . I drove down and showed him .he called area rep. he said rotors are a maintenance item and they are not going to warranty these rotors. now it will cost me 350.00 to repair my self.the problem is .It was named[GENERAL MOTORS] now its [goverment motors] no money to pay...........