I have used Gengras to service my Buick for about 6 years. Usually OK, occasionally below average, occasionally above average. This was one of the worst experiences I've ever hard with service of any kind.
I had an 8:30 AM Monday service appointment and said I needed the car by the end of the day. I was told that was fine. On Monday afternoon at 3:50 PM I called to check on when my car would be ready and was told they hadn't started looking at it, but I was 2d in line and they hoped to look at it before the end of the day. Excuses offered were "backed up from last Friday," "short-handed," etc. No apology for my inconvenience or for what would obviously be more delay.
I called Tuesday at 1:20 PM and was told they had not even started looking at my car and probably wouldn't until Wednesday. Again, no apologies, but more of the same excuses. I asked to speak with the service manager and was told he was going into a meeting but would call me back in an hour or so. I told them not to bother, because I was going to come and pick up my car.
Less than 15 minutes later I got a call from the service manager apologizing, acknowledging that the service I had gotten was unacceptable and that an 8:30 AM Monday appointment should mean something more than "when we get to it at some point this week" and stating that they were looking at my car right then. To his credit, the manager fell on his sword and apologized for the poor service several times and asked me to let them at least finish looking at my car. 25 minutes he called me to tell me they had diagnosed the problem and to his credit he offered me a substantial discount on the cost of repair in compensation for the poor service and the inconvenience of being without a car for two days. Less than two hours later the problem was fixed. So it took about 3 hours to diagnose and fix the problem, but if I hadn't said I was taking my car, it would not have been ready until at least Wednesday after lunch. Totally unacceptable when I had an appointment for first thing Monday AM and made clear I needed the car by the end of the day and was told "OK."
Gengras was by far the closest Chevy service until I moved in March. Now there is another Chevy service that is about the same distance away from where I live and I am most likely going to use them. I don't see myself going back to Gengras Chevy and I can't recommend it to others.