Engine Noise problems of the 2002 Mercedes Benz C Class

I have a 2002 Mercedes Benz c240 sedan with 78,000 miles on it. Upon leaving work two weeks ago driving down the parking lot in second gear the car started to make the worst engine noise I ever heard. I shut the car off and had it towed to a dealer and they tell me the timing chain broke. If I was traveling down an interstate and this broke and the engine lost power who knows what would have happened. This in not the first problem I had with the car I have a service file full of problems and spent a lot of time and money on things like front coil springs which also could be very dangerous when they break and I lose control of the car.