Heater installed incorrectly several years ago and when it was discoved I asked them to make corrections. He refused. Tried to say he didn't do work or that someone else must be responsible. I had original receipt. Job was old but held risk of carbon monoxide poisoning and caused air conditioning problems. He didn't care. Nasty attitiude from the minute he drove up. Even swearing.Last comment was "Have your lawyer call my lawyer."