Our heater went out last year, right smack in the middle of winter. Being an Arizona girl, this was no fun for me. I really was not sure who to deal with, having moved here only recently.
Luckily, I found a tag on our old heater that read Garoken Energy Co. I figured this must be who had serviced it before. I called them up, told them I thought they had serviced our house before we bought it, and asked if they could come take a look.
They came down that day! I was so greatful. The man who came was very patient with me and explained what had gone wrong. Even with his service call it was not too expensive.
If your heater goes out give them a call. They seem to do a really good job, though I have not much basis for comparison.