When I have a problem dealing with a U.S. company over the Internet, I go to http://finance.yahoo.com/looku.... This site will tell me the names of the top executives and the corporate postal address of a company whose stock is publicly traded, even on the most obscure exchanges. If the company's stock is not publicly traded, I then resort to Google. Sooner or later -- yes, with some effort -- I find out who is in charge and where to mail a letter.
I compose a non-threatening, literate letter to the CEO or president of the company. I explain in layman's terms what is wrong and why I won't do business with them until the problem is fixed. While the executive likely does not even see my letter, someone in his or her office will see it -- someone who has authority to correct the situation. Occasionally, the situation is indeed fixed.
After sending the letter via the U.S. Postal Service, I wait about a week. Then, I create a Web page re-creating my letter. Yes, I name names. The situation might not be fixed, but the problem and the company are now public. I carry a significant level of liability insurance.