PlanetFeedback http://www.PlanetFeedback.com
They'll help you write a gripe letter and forward it to the company. Plus, you can send copies to lawmakers.
National Association of Attorneys General http://www.NAAG.org
Find your state attorney general's contact info, and call in a complaint. AGs will take action if they see a pattern.
The Federal Trade Commission
File a complaint on line or call 1-877-FTC-HELP. http://www.ftc.gov/bcp/conline/pubs/alerts/rebatealrt.htm
RipOffReport http://www.RipOff