hidden plumbing charges

I have been in touch with various local plumbers for the replacement of a hour water cylinder. All three main quotes all quoted for various parts and left others out and all charged each item including labor. Now at first glance this looked standard until I started to break down the parts and worked out the labor. I rang back and asked to have these costs broken down and explained ask stated they did not have to which made me suspicious. I then found out the cost of labor and the cost of each part brand new. To my surprise each part quoted had at least 2-3 hours labor added. After adding up all parts and standard labor I worked out that each company was trying to over charge me by around $600. I was so angry and will now buy all the parts and find a plumber on a labor only contract to install them. I do understand that there is over head costs but feel they should be charging this into there hourly rate not try to hide them and then tell the customer they do not have to explain there pricing. I feel the need to make this issue known to the public and for trades people to be more honest with the public.