Big time sh**ty!! Definitely pursue the furnace installer for compensation. Have an independent inspector check out the original install and document his observations. You will need this if you have to go to court.
I would contact any related organizations for suggestions and input. Consumer and Corporate affairs might be a help, BBB, your munipality's permit and inspection dept. , and there is likely a provincial association that oversees and enforces standards in the HVAC industry.
After making the rounds, I would contact the incompetent installer and give them the option of settling the issue out of court before proceeding. If they make the wrong decision, it will cost you in the neighborhood of $25 to file your claim and start the legal ball rolling.
Again, sorry for your losses. The preventable ones are certainly the hardest to deal with. I hope it all works out.
Revenge is a dish best served cold...
With a side plate of steaming entrails,
And a nice Bordeaux!