Hi I know it's an old thread but I had the same problem, I have a 1999 a3 petrol 3 door quattro, driver door wouldn't shut properly and just popped open when driving part number for the catch is 8L2837016B after a very long hunt you cannot get this part number anywhere and everyone says nothing else fits, I spent hours hunting ebay just looking at the pictures to find a close match just to do some testing to see if I could get another to work, I came across one part number is 8D1837016A I got it from Lithuania and only cost me £12, it fits perfectly and works 100%
hope this will help someone in the future with this issue
