THE BRAKES HAVE NOW FOUR TIMES FAILED TO STOP THE VEHICLE. WHEN PRESSED THEY GET HARD, THEN GO DOWN TO THE FLOOR AND THERE'S A PULSATING FEELING. THE VEHICLE JUST CONTINUES TO GO TO THE FLOOR. ON THE THIRD OCCASION THAT IT HAPPENED, THE VEHICLE IN A NON-EMERGENCY SITUATION, WOULD NOT STOP IN TRAFFIC AND REAR-ENDED ANOTHER VEHICLE. IT IS DANGEROUS AND GM IS NO HELP.