Hello ...

I'm having a problem with my driverside door. Putting the key in the keyhole while trying to open it will only cause the door lock to slightly move up (not completely going up to open the door). I was thinking of just getting a keyless entry, but I can't find any that will fit my car.
Is it necessary then to change the entire driverside lock mechanism if so do I have to send it back to mercedes to get the serial #'s or are there any independent locksmiths that can fix the door lock mechanism?

thanks