Mercedes Benz repair: door locking system, mercedes benz s320, mercedes dealer

Question
I recently dropped my remote key,and it failed to work after even though i replaced the batteries.I have been opening the doors manually with the flat key for a few months now.Recently the key  freely turns within the lock cylinders without opening the doors.I can now only open the car from the trunk lock.I have been told that the lock control module has failed.Whats your opinion,and could you identify the replacement part that i would require. My car is a mercedes benz s320 long wheelbase 1995 model.  

Answer
Take it to the Mercedes dealer.
You will do more damage attempting DIY for this repair.
Attempting DIY could reach $3000.00+ USD.
It sounds like you have physical and electrical damage already.

With the dealer, you may get it fixed quickly for under $500.00 USD.