My first best guess that your car needs at least a throw-out bearing...It sounds as if it has collapsed.
When you press in the clutch pedal, this device releases the clutch by placing pressure on the pressure plate.
http://www.youtube.com/watch?v=6BaECAbapRg
Once you are in there, you may as well replace the disk and pressure plate also along with the throw-out bearing.
The tool you will need other than the standard socket set will be the clutch disk alignment tool...it shouldn't be too expensive.
If there is little rust on the car, I say shop around and find the best price for the job...
Just my opinion, but I just hate to see a Mercedes Benz go to the boneyard....
The Tenor Man