Maybe I'm getting cynical with age, but ....

I deal with it also. Being in a dealership, the customer doesn't see us as being 1 shop, they have this notion that everything with our logo on it is all connected and we all know one another.
Dealing with people is a skill, but some people just cant be dealt with. They won't be happy unless you give them something for nothing. You just can't do business that way. I've had the same issue with fuel pumps going out on people after tune ups and other work. For some reason fuel pumps are a big culprit. But I have found that people will be amazed at how well their car runs after the work we just performed, they go out and do something they rarely do anymore, fill the tank. It never fails, the fuel pump will take a crap right after that.
Most people I deal with, and talk them thru their frustration, others, well they get a rubber mallet banged on the bottom of their tank and told to never come back.
Rani, don't let idiots run you out of the business. It needs younger people to take over. We are getting older, and yes, we are looking to get out. The service desk and A/C is a lot more appealing than concrete and sweat. Everyone has to pay their dues and it doesn't matter what business your in.