I had my mechanic do some work to my '98 A6 2.8.
He replaced both rear discs and pads. He freed out and the sticking caliper that caused the problems, "replaced a seal in the caliper" and replaced both rocker cover gaskets. There were one or two minor tinkerings as well which wouldn't have totalled 30mins with no parts required. Parts were €300 approx and he had the car throughout.
He charged me €660 which wasn't the biggest shock I've ever had in itself. He said he'd go easy on the labour because I've always gone to him and given him lots of work and recommended him always. He said he'd charged me for only four of the eight hours gone into the car. By my calcs, the bill should have been an additional €300 by that reckoning. Which would be nearly a grand.
I know that he had trouble getting the right discs and I'm thinking that A) he's spinning me a yarn and he did nothing to help or B) I'm paying for the time he spent messing around with the wrong parts despite having access to the car throughout.