Bad service

After sales service of this company is very poor. We are having problems with a Jet air unit they installed about 2 years ago. It has not been working properly since day one they installed it. They have been here 3 times after begging and pleading, and every time they blame it on settings or something else, instead of just replacing the faulty unit. We are fed up and we have now started looking at at other companies for help, to resolve this problem.