Mercedes Benz repair: Central Locking System, vacuum pump, trunk area

Question
I own a C220cdi, and I have problems with locking & opening the car. I have twice replaced the batteries in the handset/key, but to no avail. I have to go right up to the car and keep zapping for maybe 10 times to get the car open. It's the same for locking, and I'm worried will it give up alltogether

Answer
sounds like your cventral locking mechanism pump is going bad. It is a vacuum pump that opens and unlocks your car. I believe it may be in your trunk area. First check your connections and fuse for your central locking vaccum system. then go to the back of tha car and try to open it up. If not go to benzworld.org and put in your profile and do a search on vacuum pump and you will find how to replace it