I look at it this way. There is always going to be somebody that thinks they were given poor service at some time by a business or business owner. I actually had this happen to me. This person went all over the social media telling stories of my work and other stuff not even related. What he did not mention in all of his stories is that he was not timing a race motor with a timing light for one and did not change the oil after each weekend of hard racing. So, the motor let go. For one, that is racing. I tell it like it is and shown that he ran a whole season on my motor and won his entire points class for the year using my "badly built motor". If it was such a bad motor how did he make it through the season to win the class at the end of the year? He did not purchase any other motors or install any until the following year. 

     Anyway, one disgruntled customer is not enough for me to change my way of doing business or building my motors. I also feel karma is real. I am not a huge shop by any means but word of mouth and good reviews are helpful. If it bothers you, write something about it stating your story and post it or submit it. Some future customers may read both and decide from there. Many will not. I have learned to use signed contracts for everything I do. That does not cover all of the complaints but it helps. If you are good at what you do, people will know the truth. Most of us know that you cannot believe much on social media anyway. We learn this from sites like Facebook and others.