When Doug Varey saw an advert on his computer offering security protection for 12 years for £556, he decided to sign up.
"I thought, per year, that's quite cheap," Doug told the BBC .
But that was far from the end of the expense, because a few months later his phone rang one night - it was his 'security advisor' with some worrying news.
They said: "Mr Varey, we've got a serious problem. We've just discovered a serious problem on your computer.
"Can you - don't put the phone down - but can you walk to your computer?"
His computer appeared to show a Russian man ordering weapons - guns, bullets, grenades - while the man on the phone told him how much of an issue this was.
"I was in total panic," Doug said.
The good news is his 'security advisor' had a solution. Upgrade his package to a new special level, costing an extra £4,000.
It was the sting in the tail of the scam he'd been tricked into signing up to.
"The money's gone," Doug said. "But what I really want is to stop other people falling for this same scam."
The good news is that a joint UK/Indian operation - in conjunction with Microsoft - has just shut down two call centres and arrested seven people suspected of involvement in the scam.
And documents sent in by Doug, a retired businessman, were used as evidence the raid.
Commander Karen Baxter of the City of London Police said it was a message to criminals, wherever they were based: "Overseas fraudsters should see this as a warning: we will use every tactic in our power to halt your pernicious criminal activities."
The police offered the following tips to stop scammers:
- Always check out callers, especially if they say they are from Microsoft, your phone provider or internet company
- Legitimate organisations will let you call back using a number you've found from a trustworthy source
- Don't assume the number displayed on your phone is real, these can be fakes by scammers
- Don't call the numbers on pop-up messages that say there is a problem with your computer
The City of London Police said anyone who thought they might have been targeted as well should contact Action Fraud.
