I am sorry to hear this happened. With my time writing service at Mercedes, this was a very common occurrence on the W203 C-Class. Unfortunately, only about 30% of the cases were solved with a new radiator and flushed transmission. Once the frictions in the trans absorb the coolant, it is almost always game over for the trans. With that said... as stated above, replace the radiator, drop the pan and the valve body, drain the converter and flush the system by tapping into the cooler lines.