The latter indeed seems to be the same problem indeed.
Funny enough, a friend of mine has an Audi A5, same problem. He went to Pon company which is the importer of Audi in the Netherlands
They fixed the problem by installing some kind of tube, and they did it for free because they knew the problem. I have to call my friend this week for more information. Then I will also contact Pon company.
When I showed the problem to the Audi dealer in my city, they reacted as if they saw it for the first time, which must have been a lie.
I will keep you updated here.