To help protect yourself from scams like this do not purchase any software or services from an unsolicited caller. NEVER give control of your computer to a third party unless you can confirm without a doubt that it is a legitimate representative of a company with whom you are already a customer.
If you think you may already have been a victim of this type of scam, it is important to change your passwords. There are also free resources you can utilize to scan your computer for malware and other harmful programs that may have been downloaded to your computer.
More information about this and other types of scams can be found at http://www.consumer.ftc.gov/articles/0076-phone-scams .