Last week I took my MKII back to the dealer for the scheduled 75,000 mile service, just like I do whenever the service indicator tells me to. This particular service is a major one that cost over $700 and included replacing the Haldex fluid. Today on my way to work, as I was slowy accelerating in a straight line away from a traffic light, on a dry day, I heard a loud bang, like I'd been rear ended. The rear tires locked up and were dragging and I immediately pulled over. Long story short, the rear differential cracked and was leaking oil. This was the result. The dealer says the service is completely unrelated and it will cost me about $6,800 to fix it! After finding the TSB warning that the final drive and Haldex each have their own drain and fill plugs, I'm wondering if there was no oil in the Haldex, could running it dry for about 200 miles have been about the right amount of time before it generated enough heat and seized up? I like the dealer and don't want to accuse them of something they didn't do, but want to find out as much as possible. An indenpendent analysis & investigation has been suggested, which might be a good idea before blindlly paying $6,800 for a repair that I don't believe is typical or reasonable for a properly maintained Audi that is in otherwise excellent condition. Any ideas or previous experience with something this catastrophic?