I've used Just In Time Furnace a number of times in the past. Each time they've been prompt, quick, and accurate with their service. Admittedly, phoning the company to book the service could be better, in that the person answering the phone isn't always the most amicable (they are professional, but not super pleasant).
The latest service was furnace and duct cleaning, and Neil and James did a great job. They were prompt, pleasant, and explained the whole process. They even came back when they realized my dryer vent had been missed (I bet other companies wouldn't). They were respectful of my space and made sure to leave things as they found them.