So you can look under my posts, as well as those of
redbarron55
Short answer you cannot find that part except used, and it is VERY difficult to find. I looked for a long time and couldn't locate.
Options are
1) Used
2) Try and swap Porsche parts (lots of discussion on t he cayenne forums about swapping module and wiring dongle on VW for Cayenne to save a few bucks, so if it works one way it shoud the other
3) Import Euro Westfalia harness and re-wire. I do not recommend this. I tried this and gave up after multiple frustration.
4) Use aftermarket - this is where i ended up. VERY easy install, plugs right into tail lights. You end up with 4 flat, but if you need full 7 you can rewire 4 flat. Just need to bring power wire from battery (etrailer has video showing wire going underneath car and through rocker panels). You can go the easy way through a bluetooth brake controller, or wire this in the hard way by bringing brake signal up and then back.