I called Button's Heating at 4pm on a Wednesday. It was 35C in the shade and had been for the last two days. My central air had conked out two days ago and we had suffered for two nights.
At 6pm THAT SAME NIGHT a guy from Button's came over and found out it was a failed thermostat, and a half hour later my A/C was back on. He went through the rebates with me and was done in an hour (he joked that the paperwork took longer than the work done, which was true).
Since my furnace is from 1961 (original to the house) and the A/C is from 1988, I've decided to use Button's this fall to replace everything.
They're absolutely fantastic and I would highly recommend them to anyone in Scarborough or the GTA, for that matter.