My A6 Allroad has been making a groaning noise when I turn at low speed and I'm fairly sure it's something in the drivetrain, maybe the centre diff or a CV joint. I took it to a general garage and they basically told me they don't touch quattro systems and suggested I go to the dealer. The dealer wants an arm and a leg just for the diagnostic, never mind the actual repair. I've been searching around and found alzaabiautocare.com/brands/audi/ which seems to focus on Audi specifically, so I'm considering giving them a call. But before I do, I wanted to ask here if anyone has experience with a shop that genuinely understands quattro drivetrains rather than just guessing. My worry is that someone unfamiliar with these systems will misdiagnose it as a wheel bearing or something and I'll end up paying for the wrong fix. Has anyone had drivetrain work done on an Audi here and actually gotten a proper diagnosis the first time?