pkash, if you are in the los angeles area, I highly recommend mr mb motors in tarzana. The owner enrique is top notch, and wont give you the run around.
If you decide your current mech is not being straight with your or seems to not know as much about these cars as he should, and you are looking to find a new mechanic, you should try mr mb motors in tarzana. 818-708-8086. It is well worth the short drive.
'92 300CE - Sold
2004 C240 - C7 Wheels
2015 ML350 - P1, Pano, Ash poplar wood, Sport Dinamica interior, Running Boards Keyless go.