This is a costly component to replace at the repair shop but it is something you can do at home.
Mercedes w220 door lock actuator removal.
Learn how to take apart the door and remove install a door lock actuator on a w211 e class mercedes benz.
You will find all the videos i made about this mercedes c200 in a playlist.
How to replace door lock actuator if the door locks in your c class are bouncing up and down or are otherwise not functioning properly the system s actuator might be broken.
Removal and putting it back is a tedious and time consuming.
Just make two 6 cuts in door inner.