Is that not just if you don't register the product? Register with HEGEL Canada, you should get the full warranty.
As for slander, etc, you can't be guilty of slander if you only relate the facts.
I feel, re-reading the post, I should add a few things, just to be safe.
The key is to stick to factual information. The mistake people make is to blend the two (facts and derogatory accusations). So don't say "the dealer is a cheat" unless you back that up with clear evidence of cheating. Keep in mind that your idea of "clear evidence" may not be the same as the legal interpretation. If you get a ruling or court order (lawsuit result) that would be clear evidence.
It's probably OK to say "I feel I was cheated" (emphasis on how the situation makes you
feel), your personal feelings are your own and perfectly valid, but keep it brief. Keep the emotions in check, maybe even create your posts or whatever in a text app and give it an hour before you re-read, edit, and post online.
Or just don't say anything at all and take your legal recourses.
In the end, you have the amp you want (apparently) and you could just walk away from the whole thing (once the details are worked out, with warranty, etc) and take a life lesson. But, it's entirely reasonable to get an answer from Consumer Protection agencies or whatever recourse you eventually decide to take.
I only say "walk" because life is short and grief (as in hassle, not bereavement) takes a toll on you. Letting go is, in the end, easier on your overall well being. Spoken as someone who has lived long and had my share of problems with people who are, basically, a-holes, and in some cases, people who were family or friends. It's a "peaceful, easy feeling" to quote the Eagles, to just get on with life and forget about stuff that gets in the way of enjoying it.
It was not a lesson I learned easily, but eventually I did learn.
In other words, put on some tunes and turn it up loud.
