If you need replacement filters and you can't get it anywhere else then by all means get from Clarkson Comfort Zone. But absolutely stay away from them if you need services or installation for your furnace. Their technicians / subcontractors are either incompetent, unqualified, or both.
In earlier Sep. my furnace failed to run and gave a fault code 61. This guy from Clarkson came in, the first thing he asked for was the manual - not a very assuring sign. He fumbled for about and hour and concluded the IFC board went bad and needed replacement. I asked him out of curiosity whether it would be the blower motor because that was what code 61 indicated. He answered affirmatively that it was the IFC because it didn't provide any voltage to his meter. So I shelled out over a thousand bucks for a new IFC board and labour.
Sure enough, after he came back and took and hour or so to install the new IFC, the same fault code appeared. By that time, he started to disassemble the unit and found that the motor module was short. They then sent another quote of another thousand dollars for a motor / module unit. Any sane person would become suspicious at that point and I eventually refused to have the guy back.
It turns out the shorting of a fail-safe device in the motor module called thermistor is a pretty common event (one just needs to do a easy Google search). I found another way to fix the motor module and my furnace was back in business. After a couple of days, I intended to test if my original suspicion was warranted. I put back my old (allegedly faulty) IFC board, and viola! It worked like a charm; and has been working since.
I called Clarkson on Sep. 9th and Georgina Myburg received my call. I mentioned 3 things to her: 1) I would not require any further service from them, 2) I have not received any receipt that they promised for the transactions they put through my credit card, 3) whether they would take back the IFC they put in through misdiagnosis. Georgina said she would check with the manger and promised to call me back thereafter.
To this day, I have not heard from them. And I am still going through dispute resolution with my credit card bank to get my money back.
It's OK if your technicians bungle once in a while, but the ethics this company displays is downright dishonest.