A very noisy - squeaky - roof ... desperate

Dear all, I wonder if anyone has experienced the problem I have and can help me find a solution, as four trips to my VW dealer has not!

I have an EOS from October 2007, and since the beginning I have been plagued by continuous squeaking of the roof from both sides whenever I hit the smallest of bumps in the road. As far as I can tell, it seems most likely to be the rubber roof seal moving against the top of the windows. It seems to be worst in cold & dry conditions and disappears when it is wet (the water presumably reduces the friction). Interestingly it also stops within 50 meters of my VW dealership

VW have tried to fix it four times - each time presumably adjusting the position of the roof, but nothing improves it. As my warranty runs out in October, I am starting to worry.

I can only assume that either the roof is wrongly positioned or loose somehow, although it opens and closes perfectly. Or, the position of the windows is either too high or too low, or something... I am quite lost.

Has anyone out there experienced anything similar? Is there a cure? Or at least a diagnosis/theory I can share with the mechanics?

Thanks in advance for any advice you can give me.