Odd that you are so strident about this issue but have not yet addressed it yourself for the pittance of a new cap.I haven't replaced the cap yet, so for me to say it was resolved would be dishonest. I don't do dealerships, and I haven't gotten to replacing the cap myself yet, but I know it's the issue.
My last Mk7, in the middle of the summer, you would actually see drips of coolant in that path. My current Mk7.5 just started doing it in the fall and I don't drive it in the winter, so I haven't addressed it. In the current car, I detect a slight odor on occasion, but not nearly as bad as my Mk7. I haven't seen any actual drips on this one yet. Just the dirt magnet vapor path.