Here is another defective part I had it replaced recently. This particular part is called the door latch as you can see the picture below. The part are made of part plastic and metal. As many W210 owner will tell you, the entire plastic parts of W210 are prone to break easily. And this is what happen to my car.
While I was working on the front passenger door panel, the door latch was jammed in a position where I have to use brute force to unjam the door handle. I had learned from this experience to never use force on plastic parts especially on a old Merz. The plastic part of the door latch broke into a few pieces and I have to tow my car to JATI Transport to have the door open professional!

When it was returned back to me I quickly order the parts from eBay for around BND$150.00 and quickly got it replaced when it arrived! Lucikly this door latch is easily available or else it would cost be BND$600 to have it replaced with OEM and labour charges.
The broken door latch went straight to the bin!
I never would thought this kind of part will break so easily especially given its a German car. Hopefully the other 3 doors is going to last longer then the front passenger door!