I had a problem were my furnace wasn't sensing a flame, so it would shut down. It wouldn't try running again for over an hour, as a safety feature of the furnace, unless I turned the power off to the furnace and let it reset.
So I called a couple places and told them the problem. They quoted me a visit fee of ~$200. Then my buddy told me ATCO would come look at my furnace for free. So I called them, was told they couldn't come by for a few days. I managed with my furnace till then. When the guy came by it literally took him 10min to clean it out a little and clean off the sensor that was causing the problem. All this for free.
He said thank you and told me how to prevent it in the future.
Pretty good overall. Saved me $200 bucks.