1994 Mercury Cougar repair shop bill

Hello. I had bought a winter car. It was determined that the car needed a fuel pump and water pump by a repair shop owned by friend of a friend. I was told that this would be $700 for parts and labor. I figured that this guy would not misquote me as he knew my friend for years. I agreed. I was then called and told that during the repair he had broken a water pump bypass tube during the repair and was leaking worse. He told me that it will cost me an additional $275 to fix this. Checked at another shop and with their computer they looked up labor rates. Original repair should have been $475 parts and labor and they should include the additional repair in the labor. Now my question is: Is the shop legally responsible to fix a part that was damaged during their repair?