Incompetent and unprofessional.  I took my car in because it developed a miss, the kind typical of something wrong with the ignition system.  I specifically asked if they did computer diagnostics and they assured me they did.  They called me later with the results - said it needed the carburetor rebuilt for around $400.  I went over to pick up the car and decide what to do.  I asked to see a printout of the computer diagnostic so i could see if the ignition system had checked out OK.  He didn't have a printout.  When I asked more about their \"computer system\" his answers got really weaselly.  I paid them the Diagnostic fee.  I didn't believe them and took the care to a different shop that I like but that was much farther away to have them check it.  They checked and said the problem was a bad spark plug that was all fouled and showed me the plug, it was a mess.  They had put in a new plug to replace it and they car ran fine.  They said it would probably foul it again because the valve stem seals were leaking.  They also said there was nothing wrong with the carburetor and the car ran great when I drove away.   I went back to the Shell station with the results and asked to speak to the owner.  Supposedly he wasn't there.  I came back later and the same guy was there and I finally pinned him down to at least admit he was in charge and showed him the results from the second shop and explained that with the 1 new $2 plug the problem was fixed.  Asked him how such a clearly bad plug, which I showed him, would not have literally jumped off the computer screen of his \"computer diagnostics\".  He just try to BS his way around without answering.  I told him I thought they owed me my money back for their \"diagnosis\" since it was so clearly wrong.  He refused to even consider it.    I wouldn't trust this place to wash my windows much less do any work on my car.