Radiator problems of the 2003 Mercedes Benz C320

This happened in my 2003 C320 at 54,000 miles. I initially noticed a light rubbing or grinding while accelerating, with light vibration. At the dealership I was told I would need a new torque converter, new radiator, and a fluid flush. The radiator fluid was mixing with the transmission fluid. After those repairs, my C320 was still shifting hard and the grinding noise was still there. It turns out the transmission was ruined as well. Two replacement transmissions were needed until it was ready to be picked up. I've been told that the mixed fluids are not uncommon in this model and yet mbusa has made very little effort to answer my questions.