I’ve had good experiences with POWAY IMPORT CAR SPECIALIST, 13502 Pomerado Rd, Poway, CA 92064
(858) 486-3206. Scott is good about explaining his findings and possible options, including ways of avoiding expensive work. I haven’t had any really major repairs done, mainly because I am cheap and learned to tolerate my A4’s idiosyncrasies rather than throw money at them. I agree on another poster’s point about the pathetic reliability of German cars. I have forsworn that the next time my car develops >$1000 problem, it gets immediately traded in for a Honda or something similar.
Good luck.