Credit controller Linda Reay was sorting the daily pile of bills back in 2005 at the bed-manufacturing factory where she worked near Carlisle, an industrial city in northwestern England. Then she took a phone call that would destroy her retirement dreams.

The smooth-talking caller identified himself as a London stockbroker named Robert Samuel. Nearing retirement from her £17,000-a-year job, Reay took the salesman's advice to invest in the stock market. Within six months, her family had sent more than £13,000 ($20,570) to a St. Lucia-based company named Damak Group to invest in ValiRx Plc, which Samuel said was developing cancer-fighting therapies. Although ValiRx is a real London-based drugmaker, the investment pitch was pure fiction and Reay would never see her money again.

"I thought you could make a little bit from what you've got," says Reay, now 61 and retired. "You see that share prices can go up in a few days and you make money, so I thought maybe it could happen to me. It sounded above board."

Robert Samuel was a false name, just one of a group of cocaine-fuelled, self-styled "telesales terrorists" reading from a script 960 miles away in Barcelona. It was there that Damak preyed on investors with a series of share-selling scams known as boiler rooms.

Reay is among 450 victims ripped off in the space of six months by Damak's cold-callers. A two-year police investigation culminated in four people being sent to jail in April, and police officers are still on the hunt for the £2.4 million stolen from investors and funnelled through accounts in Hong Kong, St. Lucia and Spain. That's just a fraction of the £300 million that police estimate boiler rooms will steal from UK investors this year compared with £100 million in 2007.

They say cold-calling share sellers are finding it easier to lure victims as people look for quicker returns in the wake of the financial crisis.

Spain is the friendliest locale for boiler rooms that target UK investors, investigators say. Its major cities are only a two-hour flight from London, and the country is home to 761,000 expatriate Britons, according to the UK Foreign Office, making it an ideal place to set up a stock-selling operation aimed at English speakers. About one-third of all known boiler rooms are located in Spain, according to data from the UK Financial Services Authority.

That's why British tabloid newspapers refer to the 1,000-mile stretch of Mediterranean coastline — which runs from Barcelona in the northeast to the resort of Marbella in the south — as the 'Costa del Crime'.

Spain's beach communities gained notoriety as a safe haven for British criminals in the early 1980s, when convicted robber Ronnie Knight spent a decade there on the run. A century-old extradition agreement between the UK and Spain lapsed in 1978 amid tensions over the status of Gibraltar, the self-governing British territory that Spain claims as its own.

While the agreement was re-established in 1985 just before Spain joined the European Community, the predecessor to the European Union, the country didn't shake off its image as a gangster refuge.

"What do boiler rooms want?" asks Michael Levi, a professor of criminology at the University of Cardiff in Wales, who has written books on corporate crime. "They want a nice environment, and that means good telecoms and a local police and judiciary that aren't too bothered about them. That has been true for Spain."

Small investors aren't the only victims of the con artists. ValiRx, which is listed on London's Alternative Investment Market, says its legitimate business and good name have been damaged by the Damak scam.

Police say there is one sure way to avoid falling victim to a boiler room scam. If a stranger calls you up out of the blue and asks about your investments, put the phone down - no matter how well spoken he is.