some people you just cant please, you know this.
if you want to keep him then you have to explain things. People try that with us too on old cars, its old so it cost less. I explain, its old, less helpful (computer systems), rusty and easy to break stuff, so, it will cost you more to fix it. If you dont want to keep him, explain that your prices are your prices, those people on the internet are not coming down here to fix your car. Auto repair prices are different here in tx as they are in california the same as cost of living and home prices.
it really isnt any different than any other customer, some you have to spend extra time on and others you dont.