I've had a mysterious problem with my traction control on my TT Mark 1 Quattro. I took the car to Camden GTI today and they replaced my Haldex controller, they had a mint used one for $250! and for the first time in about 15 years, the car has no fault codes! They do great work and have a wrecking yard full of GTIs and Audis. I highly recommend them for anyone running an older Audi.