Sorry, I misread your post...
http://vagparts.2am.fi/index.php?part=053905205D
The above link seems to be the part, but as you say these seem to come with the wrong cap.
I have a vested interest in solving this- you never know when I will get the same problem
I'm hoping to replace the o-ring, as part of the hunt for why my Coupe goes through so much oil. (Yes, valve stem seals are a concern, but 1litre a month is a lot, I think)
Good Luck!