Electrical System Engineer. Check engine light is on

What is your question?

My car CLK350 have 33K. The check engine light is on and the transmission is not shift properly. Mercedes dealer charge me 2500 to fix this problem. Just replace the electrical valve body and perform adaptation to transmission control module. Do you think the car running only 33K will have the transmission problem? I have asked the shop give me the diagnostic report but they refuse it. Does anyone know what cause the problem of the transmission like this. I really want to know why the luxury car is running only 33K had the transmission problems