Had misdiagnosis and caused me extra money and headache.
They diagnosed my car as having to replace the a/c compressor which they said would cost around $1600 (2007 dodge sprinter/mercedes). I thought that was a lot so I wanted a second opinion. I took it to a dealership and they said I only needed to change the freon pipe/tube as it had a leak in it. He said Firestone misdiagnosed it because without freon pressure the compressor will not get power. Long of it short, the repair cost me $400 at a the dealership. $300 for the tube and $100 for the labor.
I too wanted to save a couple of bucks by going to an independent mechanic, but I could have paid out of my @#$ had I not gotten a second opinion.
From this point forward I will go only to dealership for both of my vehicles.