If they won't let you file a complaint on the company, why don't you file a dispute on your credit file? As far as I know, they HAVE to at least SHOW in your credit report that the particular entry is disputed.
I don't know if the CB (Credit Bureau) in your area will send you a free report if you ask for it within 60 days after you are denied credit, insurance or a rental dwelling opportunity based at least in part on information in a credit report. Check with your CB. If so, you will probably also receive other information like your credit rights and a CREDIT REPORT DISPUTE FORM with instructions. Just remember that you will catch more flies with honey then with vinegar.....
Good Luck