WE WERE DRIVING OUR BUICK ENCLAVE ON I 94 EXPRESSWAY NEAR MERRIMAN ROAD NEAR DETROIT METRO AIRPORT WHEN WE HIT A CONSTRUCTION ZONE. WE SLOWED DOWN TO 15 MPH WHEN CAR BEHIND HIT US GOING FULL HIGHWAY SPEED. THERE WERE 4 PEOPLE IN THE CAR. 2 OF THE PEOPLE (THE DRIVER AND PASSENGER BEHIND THE DRIVER) DID NOT HAVE THE SHOULDER SEAT BELT HOLD. THE DRIVER HIT THE STEERING WHEEL AND THE PASSENGER HIT THE BACK OF THE DRIVERS SEAT. THE AIRBAG DID NOT DEPLOY. THE ANSWER FROM GM WAS A SIMPLE 'WELL IT SHOULD HAVE'. WE BOUGHT THE CAR WITH 13000 MILES FROM TODD WENDELL IN WESTLAND MICHIGAN. THEY SAID WHEN THEY CERTIFY A USED CAR THEY DO NOT CHECK SEAT BELTS. THEY SAID THEY WOULD CHECK ON THAT A WEEK AGO AND CALL BACK (THEY DID NOT). CALLED BACK 4 DAYS AGO AND NO RETURN CALL. GM SAID THEY WERE GOING TO LOOK AT THE CAR BUT NEVER DID. I AM ABOUT READY TO SEND TITLE TO AAA AND THE CAR WILL BE GONE. ENCLAVES HAVE A HISTORY OF SEAT BELT FAILURE. I AM HERE TO SAY THEY HAVE NOT FIXED THE PROBLEM..THEY NEED TO DEAL WITH THIS BEFORE OTHERS ARE HURT!