Error.. Dealership "would not" tell my mechanic other then it's the transmission on 2001 Mercedes-Benz C320

If anyone has had this issue.. Please let me know. tks

Asked by for the 2001 Mercedes-Benz C320
dealership only good for selling cars. worsed place to go for repairs. take it to a tranny shop for diagnostic run. tranny tech. will advise.