Had a conversation today with a customer that I had repaired his duramax about two months ago. Says he was happy with the repair but I charged about $1500 too much. Says he called and got prices on parts after repair and says he can get parts for less. Try to explain that I have to mark parts up to make a profit. That is what your labor is for. Says other shops only charge what you can get parts for. How do you deal with customers like this? I personally know my labor and price markups are less than other shops. By the way repair was both head gaskets, heads rebuilt and three new injectors on a duramax diesel, A very expensive repair, but also advised him not to buy the truck originally.