We are a contractor that works on construction projects, appointed by the builder. On a recent project we have back-charged for a supposed mistake we made in cutting out space to put our equipment in a place without checking the right location with the builder. The back charge is sizeable and going through correspondence, I am unable to see how we are at fault. We were given no formal drawings or locations, and were asked to make a recommendation on location, which we have in writing, and have followed this particular recommendation. We didn't feel the need to ask before moving forward.
What is the process if the builder is willing to hold back payment without considering our viewpoint?