Talking of independents in SoCal, I once had the brakes of my X5 changed
at Swiss Motors (I think they are in Culver City). I had the most horrible
experience. They charged for the sensor, but never replaced it. After a month
when the brake warning started to show again I took it back to them and
they said something else was wrong and were asking for $250 for
diagnosis! I smelled the rat... Then I took it to my local mechanic in
the bay area and he told me that the sensor had never been replaced.
Once that was done it was back to normal.

So be careful where you take it. Avoid Swiss Motors...