The Master Mechanic Inc

I recently had a terrible experience at a master mechanic. My car Failed the safety Inspection, so they told me they not gonna charge me again. I Paid $250. After a week I did my repair by myself because they charged me almost double the price and labor extra. On Monday l, I called them to get a safety Appointment, After I told him I fixed it By Myself then they told me they gonna charge me again for safety. He talked to me in a very bad way and told me why I fixed my car by myself.