Go to the VW dealer and point them out on the ETKA screen. It's the only way. Internet numbers are usually out of date, unless someone has done the same job very recently.
Oemepc.com is a good resource for part numbers, but again, I'm not sure how recent they are.
The last 10 part numbers I've procured online have, half of them were either completely wrong or superseded with a new one by VW.