Rallye Lexus

Bought an L/Certified GS 350 from this dealer. First problem was the car had some work done to the exhaust system. When the rattling from the rear became too much to deal with, I took it to a local Lexus dealer; because Rallye was too far away. They found a screw drilled through the exhaust pipe to keep it in place. I told Rallye about this and showed them pictures. In short, they said, it wasn't their problem! Now a new issue just surfaced. I bought the car with approx. 14,600 miles and have driven it about 5500 miles when I first heard a disturbing noise. When I fully turn the wheel in either direction, I am getting a loud rumbling like noise. I'm told the car needs completely new brakes and rotors, front and rear! Remember the car had less then 15K in miles and I added about 5500 miles before this issue arose and it was branded with the very desirable L/Certification, passing a rigorous 161 point inspection. That L/Certified report said of the Rotors and Calipers, 'no excessive wear, warpage or leakage'. And Rallye's response? In short, not our problem!