2001 Other Mercedes Benz Models

Ive got a 2001 mercedes clk230 kompressor, driving along a road untill it broke down had it recovered in to a garage and said that the problem was that the timing chain had snaped, witch causes the engine casing to have a chunk out of it, had the timing chain replaced (new), engine casing repalced (2nd Hand), had the sump removed to try and find the chunk that was broke off the engine casing wicth was found and cleaned the sump, repalced the sump, they put the car back together with new oil and oil filter, I had the car back and was fine, about a month later the car broke down again had it recovered to the garage they took the car apart and said that the crank shaft had snapped, had the crank shaft replaced, about two weeks later the same thing happed again, would you be able to help me, thanks