All Time Heating Plumbing

Very bad experience. I have never ever had such a worst ever services in my life. The guy, Steve, installed a new boiler and tank-less hot water tank in my house to replace my old boiler and old hot water tank. The whole installation was done by other 2 guys, he just came in once in a while during the whole installation day.
They started in the morning of the day, and he promised to be done within several hours, but the reality was that it was done by the midnight, yes, about 12 AM midnight. After the installation, my nightmare just started. I called him to fix several problems until he stopped coming to fix the biggest one left behind.
The biggest one was very noisy knocking sound from my new heating system which he installed. I told him that my boiler started to give out the knocking noise every night just like someone hammering on the pipe right after the new installation and fixing. But he didn't come but just try to foolish me and said that was normal and should be slowly solved by itself. During that time, the noise was not too loud and endurable. But I know there should be something wrong with the heating system. He never tried to fix it but only tried to make excuse. And even worse, he told me some his stories and tried to scare me away from him when the last time he came to my house. Now, my heating system really got almost dead. One night around 2 am of last November 2016, my heating system fired very loud "bang bang ..." noise constantly like machine gun firing in my house and woke up all my family members. I tried to contact him but he didn't answer his phone and not even return my call. So, I have to pay a lot to other plumbing guy to fix it.
Since the beginning of the installation until the last time he came to my house, I never saw him to touch my heating system. Installation and other couple of times problem fixing were all done by other 2 guys.
There are still more worse details about this story. Because it would be too much and might be like a novel to write all down here.
I was thinking to give him a chance and really didn't want to give him any negative review before, but now my heating system was down and he didn't response to me.
So I thinks he doesn't really care about his reputation, I will satisfy him and have others know how this guy is.