Front Suspension problems of the 2008 Mercedes Benz GL450

On April 30th 2009 while driving car slipped into low gear on its own. On may 1st while pulling out of a driveway and going to make a left turn on a major road the car again slipped into low gear. Ten minutes later while easing into a shopping center parking spot the car shot forward and crashed into a concrete pillar. I was driving the car and injured my wrist and my mother who was in the passenger seat injured her ankle. The air bags didn't deploy. Car was sent to authorized mercedes auto body shop repaired then sent to mercedes dealership where they checked the car and said no problems were found with the car. On July 7th while stopped at a red light at railroad tracks the light turned green I stepped on the accelerator and the car didn't move I couldn't understand what was the matter and when I looked at the gear indicator the car was in low gear which happened again on its own. Also in April 2008 the vehicle front suspension system failed and mercedes replaced suspension system.