Send a written request to each of the three agencies (it used to be $10 each): Transunion, Equifax, and Experian and request to have your credit reports frozen. I'm sure you can find the form letters online or at the three individual sites....don't remember what I used many years ago. That's all it takes...those "services" are a rip-off imo.
edited: A quick search turned up this link (lots of 'em out there):
http://consumerist.com/2007/11/how-to-freeze-your-credit-report.html