Sergmont:
Sorry you had this terrible experience. I don't recall many complaints about delivered goods, but I think this is fairly new, and not widely used.
But there are many complaints about treadmills, usually for poor quality. These are products that are heavy and difficult to move, so that adds more complexity.
The biggest issue I see is that it was misrepresented as being new, when in fact it a used demonstration model. You should be entitled to return it based just on that, although you might have to settle for just a replacement. The return is due entirely to their error, so there is no reason you should have to pay any of the costs for them to 'make it right'.
That being said, some Canadian Tire stores are regarded as helpful to customers, while many are known to be terrible for service. Some start out OK, and then a bad owner/manager takes over & it goes bad.
You could try the main 1-800 number for CT Customer Service. Sometimes they will help, but often they just say to go back the store, which leaves you hanging.
Another option is to contact your provincial consumer's ministry. They might help settle this for you.
Also, if it comes down to a lawsuit, they can tell you which laws apply (usually rejecting goods that were misrepresented, in this case as being used). The laws will likely allow a remedy for the costs you experienced.
Some consumers report getting a settlement as soon as they file the suit. Others have to go before a judge, but then CT settles.
There is also the option of just taking your lumps, keeping the damn thing, and putting in a service call, under the warranty, for the noise.
Again, sorry to hear about your troubles. Some people say they like Crappy Tire, but there's a growing body of people who swear they have gone way down hill in recent years, and just want to keep you money, no matter what.
Good luck with this, and keep us informed if anything develops!