Brake Disc Pads problems of the 2009 Toyota Matrix

Over heating brake pads. 2009 Toyota Matrix. Front disc brakes producing a grinding sound consistent with a brake pad that's worn down and needs to be replaced. Brake pads still have 40 % life left according to world Toyota of chamblee, georgia. Dealer says brake pads are over heating dealer says problem can be fixed if pads are replaced but wont replace pads at their expense stating pads are not covered by warranty.