My air conditioner had been out for two days because the first person I called didn't show up (and didn't bother letting me know why). The next person I called told me my unit could not be repaired and I needed a new one which they would be glad to install. Before going any further, I decided to get a second opinion. Not knowing who to call next I asked my neighbor who he used and he said GSM. I called and scheduled an appointment. Thirty minutes before the scheduled time the GSM technician called to tell me he was on his way. He was very courteous and after checking things out he told me I did not need a new system. He made the repair that afternoon and within an hour my central air was working great. I highly recommend GSM and plan on using them whenever I have a problem.