really like my "new to me" A6 and I bought it with the Audi certified warranty. My initial dealing with the dealer were less than pleasant when I challenged them on the condition of the car that had supposedly been gone through from top to bottom. I had to take my complaint of bad tires (worn and cut) to the General Manager having been told where I could go by the used car manager. I now have another issue and would like some opinions on approach before I run the gauntlet again with the dealer.

Both C pillars (is that the right term, near the back window?) had water stains when I bought the car and I assumed someone has left the sunroof open at some point so I removed the stains. They are now back again, but did not return immediately despite heavy rain. I can never feel the pillars wet, but the stains are real. Has anyone else experiences this and/or could suggest a cause?

I would appreciate any help, Thanks.