David Parnell bravely admitted to falling for a scam. He talked us through how an issue with updating a GPS device led him to looking online for answers. The site he found included the name of the manufacturer so looked genuine but was anything but. His "helper" offered to investigate why the update wasn't working by checking David's machine. Of course, many genuine help desks will also take over your screen so suspicions were not aroused at this point. However, when David was told he'd need to pay Apple for renewal of his firewall licence (!) and he then saw his Keychain Access program appear in the dock, he hastily shut down.
Whilst it's probable that no sensitive information had been harvested at that stage and he certainly hadn't given card details, he contacted his bank and had all his cards cancelled, causing more than a little inconvenience waiting for new ones. So be on your guard - most scams are aimed at fooling us rather than our computers.