My combi boiler was fitted at the end of December 2020. It failed on 21st Jan 2022. Viessman arranged for an engineer to solve the problem the following Tues. He was temporarily successful, but after 3 or 4 hours it failed again. After long waits on the telephone I spoke to an operative who sent me an email stating that an engineer would ring me between 8 00 and 10 00 am Friday. It didn't happen. I have spent the day emailing and phoning and listening to promises that they would ring back. That hasn't happened either. Now I am again stuck on the telephone waiting for someone to answer. I am horrified that a supposedly reputable firm treats its customers with such contempt. I may add that I am almost 80 years old and feel the cold badly. Desperately bad service. You should be ashamed.