Sorry to hear your experience was such a disaster. As someone who has been in the POS industry almost a decade now, I have been involved in few a of those disaters myself, and they are not fun. Sometimes they were the result of software bugs (which unfortunatey all POS systems have), sometimes poor planning by the companies installing them (like mistakes by employees), and sometimes the result of the client (unrealistic expectations, poor description of problems, etc).
Most businesses and clients are reasonable, and as long as you have a company that works hard to get things to an acceptable level, no matter how bad things may have been intitally, that's about all you can ask for. In this case, it doesn't sound like they did that... but again, I don't know the specifics of your situation. As a business owner, I am always curious to get a customers perspective, and I will check out your site to see what transpired.
At this point, I am not sure if the situation has resulted in litigation (as angry as you are, I assume it is being considered or is in the works). Nor am I am I familiar with Canadian law. But I caution you to becareful with that site and what is posted on it.... as justified as you may feel in engaging in such an endeavor, you don't want it to back fire and end up adding insult to injury by having them sue you for libel or some other form of defamation (on top of being the head aches you've already gotten from your POS system). Posting on Tek-tips or some other forum that you had a miserable experience is one thing. Dedicating a website to destroying a companies reputaition, however, might easily be viewed by a court of law as spiteful and vindictive, as well as interfering with commerce.
I am not trying to suggest you don't deserve to be angry, or even infuriated... just passing along some friendly advice. I am curious to know if you've chose another POS system. Like I said, I plan to check out your website and will probably have a question or two later.
Hope it goes better for you next time!
