I've talked to more than a dozen shops. The shops that have enough knowledge/skill to actually understand the issue won't touch it. The shops that have no idea what's going on will gladly/blindly accept the challenge. I made decent acquaintance with one shop owner and he finally agreed to do it but quoted $1,000 and it came with the mutual agreement that there was a small possibility that attempting the repair might damage the roof. There may be a few shops out there that can handle it, but I'm guessing 99% of shops won't touch it unless you have a repertoire with them. Surprisingly BMW only charges $2,000 for a new roof
https://www.getbmwparts.com/oem-part...10-54108045327
I ended up never getting mine fixed by the shop because it's become a track car. I've been thinking about lightly sanding or shaving away with a razor blade the trouble area, spraying it with plastidip to smooth it out and wrapping it in gloss black or carbon fiber vinyl