Had a problem with the rear door latch on my 200tdi and discovered it was a small tension spring that was causing the problem that I couldn't open the back door without leaning over the back seat to hold the locking mechanism up whilst opening the door.
Looked everywhere I could think of in town to find someone who would supply these small springs.
Eventually, I did an image search on Google and came up with this site:
No way was I going to buy a complete latch.
So hopefully this will help someone else on here.