MAZDA RX-8: CAR WAS PARKED AT THE TOP OF A GRADUAL SLOPE, WITH PARKING BRAKE FIRMLY PULLED UP. NO MORE THAN 5 MINUTES LATER, THE CAR HAD BACKED UP INTO BOTTOM OF A DITCH. THE CAR WAS GIVEN AN ESTIMATE OF OVER $15,000 WORTH OF DAMAGE DUE TO THE FAULTY BRAKE. WITNESSES AT THE SCENE CONFIRM THAT THE PARKING BRAKE WAS SET.