Affiliate Marketing Secrets

I run a website that provides profiles and contact information about certain businesses which rely on hiring contractors. I basically help people get in contact with these businesses to get hired. So, I got a Cease and desist letter from one of the companies (not a court order, basically a warning) and I’m wondering if I’m really doing anything wrong and should respond. They claim I am advertising their business (which who the hell turns down free advertising?!) in ways that they do not approve. I do have a disclaimer on my site which states that I am not affiliated with any of the companies mentioned on the site. Isn’t that enough in my defense?