2009 MERCEDES BENZ ML63 Engine Problems

WHILE MY WIFE WAS DRIVING OUR 2009 MERCEDES BENZ ML63, AT APPROX 65 MPH, ON THE 101 LOOP IN SCOTTSDALE AZ, SHE EXPERIENCED COMPLETE ENGINE FAILURE. THE ENGINE COMPLETELY SHUT DOWN ON HER. SHE LUCKILY WAS ABLE TO COAST OVER TWO LANES TO HER RIGHT TO AN EXIT RAMP. THE CAR CAME TO REST AT THE BOTTOM OF THE RAMP W/ NO ENGINE POWER WHATSOEVER. MY WIFE WAS PETRIFIED. THE CAR WAS TOWED FIRST TO AAA AND THEN TO SCHUMACHER EUROPEAN, LTD (A MERCEDES-BENZ DEALERSHIP) IN PHOENIX, AZ. ACCORDING TO SCHUMACHER EUROPEAN, LTD THE CAUSE OF THE ENGINE FAILURE WAS A BLOWN HEAD GASKET DUE TO BROKEN HEAD BOLTS. THE REPAIR ESTIMATE WE RECEIVED FROM SCHUMACHER WAS BETWEEN $6,000 - $25,000 DEPENDING ON THE AMOUNT OF DAMAGE DONE TO THE ENGINE. MERCEDES-BENZ USA HAS HAD A KNOWN ISSUE W/ DEFECTIVE HEAD BOLTS. THEY ISSUED TECHNICAL SERVICE BULLETINS BACK IN 2011...