I'm sorry to hear you're experiencing problems. My purpose is not to post in defense of WOT. As with ALL link scanners, their ratings are not 100% accurate, 100% of the time. For the most part they are. My hopes are to point you in a direction, where you might get the help you need.
You wrote, "The only reason that they rated our business badly was because one of our staff posted one comment on their forum". WOT uses various sources and methods to rate their reviews. While they do consider user input, it's not their sole source of information. Read "How WOT ratings work" at their Help Center.
If you feel your site was unfairly rated, they WILL investigate the issue. I know this for a fact, from a site owner who had their rating "turned around", after going through the proper channels.
If you haven't done so already, I would suggest putting your efforts into:
Contacting them directly: http://www.mywot.com/en/contact
I would also ask the site be re-evaluated by posting at their forum. ("Read this before requesting an evaluation")
As stated above, link scanners are not 100% accurate. We take this into consideration, when suggesting to our members, they not be without this (important) type of security tool. The benefits FAR outweigh the risks of going without it.
Best of luck..