I have a rather complicated and delicate prosthesis. It is my only means of eating, drinking or speaking. The first and only time he adjusted it he left rough surfaces which I attempted to fix myself after years of practice but needed a professional to fix. While smoothing the surfaces he held the piece by the clasps which caused them to shift. When he went to fix them he broke one off. It is now unwearable!! He acted like it was no big deal, was apologetic but did not realize the severity of what he had done. It will cost several thousand dollars to get a new one and he won't be the one to make it!!!