Mark Out Problem.

I received a letter in mail regarding an emergency mark out. It stating that there is a possible violation. What had happened is that it was the first time working for this builder and he called me stating that he wanted to replaced a water service the next day. He stated the water service was leaking and needed to be replaced. The contractor that he normally used has been increasing acting irrational and he believed that he mayne using drugs. Well I called the mark out and the next day while I was there, the former contractor showed up, making a big deal about the mark out. Saying that he was going to complain about it. Well I guess he did. The letter is requesting a response in writing, Any ideas how to respond to this? The service it self was no problem. The water was turned off prior to me getting there and there was 3 or for old services in the ground when I dug,

Mark Out Problem.