Mersey Heating And Air Conditioning

Horrible experience! My advice is to avoid these people.
Here's my story. It's moderately long, but I wanted to be clear.

Mersey had been doing the annual maintenance on our furnace for the last 8 years or so and every year in the past they indicated that our furnace was too big for the house and that it was cycling off more than it should and they left it at that.
This year, cleaning was done as usual, but then the cleaning guy had his supervisor come over to check things out. His supervisor came over and indicated that we have a problem with the furnace cycling off - something that we have known for years. He had us open all of the vents and remove the air filter and he then noted that the furnace was no longer cycling off. End of issue? No.

He then told me that I need to get a new furnace and that he could send someone the next day to make arrangements. When I asked him if there were any other options, he indicated that there were none. (Now remember, he had already resolved the issue by opening all of the vents and removing the filter.)
I told him that I would discuss the situation with my wife and get back to them. At this point, he indicated that he had to "red tag" the furnace. For those of you who don't know, an HVAC technician can attach such a warning tag, or "red tag", to your furnace, forcing you to correct an issue or have your gas disconnected by Enbridge. So he attached a red tag to our furnace and he gave us 14 days to correct the "issue". Now, the Enbridge rules state that you must clear the issue 5 business days before the indicated number of days on the tag - so now, we're down from 14 days to 7 days to clear the issue, because we have to include a weekend.

The supervisor told me that he was obligated to "red tag" me for safety reasons and to avoid liability, but is this a valid reason given that it had been an on-going situation for years and that he resolved the issue before he issued the tag? I don't think so. And even if you accept their reasoning, I believe it was unfair of them to provide us with such a short time period to act.

So... I had 7 days to correct the issue, or Enbridge would disconnect my gas:
Mersey had indicated that the only way to fix the problem was to have them install a new furnace but I found someone to update our duct work and solve the so-called "problem" at far less expense than a new furnace.

Mersey put us though a lot of anxiety and trouble. We wasted a lot of time resolving this issue. I feel that their treatment of us was very unfair. Were they trying to goad us into spending more money than necessary or were they simply incompetent in not recognizing alternative solutions? Either way, I would avoid these people based on my experience.