By Sarah Toyne
BBC News Online consumer affairs reporter
It is under-reported, expensive - and the victims are often the most vulnerable sections of the community.
Britons are increasingly targeted by overseas so-called "boiler room" scams, operating out of telesales centres from Canada to Spain.
Using high-pressured sales techniques, people are lured into handing over their hard-earned cash by unscrupulous salesmen.
Britons who fall for the lottery and prize draw scams - which demand a fee to access non-existent prizes - are now losing £10m a year, some of them as a direct result of telesales, according to the UK trading watchdog.
Meanwhile, people continue to invest their money in phoney shares - many unaware until they sell them that they are worthless.
British consumers appear easy prey for the men and women operating the
get rich quick schemes.
The operations are nicknamed "boiler rooms" after the film, which portrayed the high-pressured but profitable world of cold calling.
The Office of Fair Trading says those targeted are the most vulnerable sections of the community - the old and the lonely.
Consumers have little chance of getting their money back, because the firms are unauthorised - and are usually based overseas.
This means it is also hard for British authorities to close them down.
How to avoid share scams
Always check whether the company is authorised in the UK
Never give your bank account numbers, credit card numbers or other personal information
Never sign up to anything immediately
Remember, that if it is a genuine offer, there will usually be a 'cooling off' period
If in doubt, get independent advice.
If you're told to keep the information confidential alarm bells should start ringing
Don't fall for investments that promise spectacular profits or risk-free returns
Get in the habit of deleting any emails you receive promoting get-rich-quick schemes
Don't get carried away by the promise that you will make a fast buck
Share scams lure people by post, e-mail or through advertising their sales on the internet.
One common tactic is to offer a free research report into a company in which you hold shares, or a free gift or a discount on their dealing charges.
People are often unaware that when they reply to the mailshot they have agreed to be contacted by the firm in the future.
Once called, consumers are subjected to high-pressure selling techniques - and often part with their cash.
But the firms never give out phone contact numbers, and they can simply change names - and set-up shop elsewhere, making redress virtually impossible.
As the companies are based overseas, they are not authorised by the Financial Services Authority, the City watchdog.
This means that if something goes wrong they are not covered by an investor compensation scheme.
Tony Scutt of the Guild of Shareholders, says the reported cases could be the tip of the iceberg - and many people may not realise they have been duped.
"Many people just fail to realise they are victims, he says.
"They just think they are sitting on a good investment - and never think to ask for proof of what the value is."
You've won the lottery
The OFT says it is receiving more complaints about lottery and prize draw scams.
Lottery and prize draw scams
Prize draw scam: A person is told they have won a prize, and are asked to send a "processing fee"
Lottery scam: People are told they have won the lottery, but told that they must pay a fee, usually a tax, before the money can be released
With prize draw scams, people are told they have won a prize - and are asked to send a "processing fee".
They can hand over hundreds of pounds, but the prize never materialises.
With lottery scams, people are told they have won the lottery, but then told they must pay a fee before the money can be released. But more than not the money never turns up.
The OFT is working with Canadian authorities to crackdown on the operations.
In July and August this year thousands of pounds of UK consumers' money was intercepted in a joint operation.
But the OFT says while there are large amounts of money at stake, the extent of the problem is "largely unreported".
The FSA, which is in charge of dealing with financial scams, says it is also working with regulators, but admits it can be very difficult to catch the perpetrators.
It says consumer awareness is the best way to tackle the problem.
"The best way to tackle this is through consumer education", a spokesman says.
"The key point is that you should always check that someone is authorised before you do business with them."
Consumers can get useful advice on common financial scams, and how to deal with them from the Consumer Help section of its website.
Have you been a victim of one of these scams? Send us your comments, using the postform at the top right-hand side of the story:
I've been duped into believing I won a prize, I thought it was a bit suspicious but then I was also called and thought this actually may be real. I eventually fell for the scam due to my excitement.
Its important to remember, particularly in today's world that nobody gets rich giving things away! So people should not fall for notices saying "You've won ten grand" or "send £125 and receive your free 40" TV" No company will give you anything without something substantial in return. Get rich quick schemes do not exist and as an investor myself I can say you need to think with your mind and not your back pocket!
Rob , England
I got a text saying I had won £1000 and all I had to do was claim it by calling a number. I did and I was on the phone for half and hour to learn that I had just won £100 of holiday vouchers and I needed to send off for them. The bill came through and with the one phone call I had worked up a massive bill.
I've seen another scam letter that is sent to small businesses claiming to be a registration form for data protection and asking for a fee.
Falling for a 'Call now to claim your prize' text message is just Mother Natures way of telling you to avoid sharp objects.
I had a man claiming to be from my credit card provider offering me an interest free loan of nearly £20,000 recently. No catches, no tricks, just give the word and the money goes into my bank account. When I asked him to put something in the post so I could read it he explained that they "didn't do that". One week later he called again asking if I wanted to go ahead, so I told him again that I wasn't going to do anything until I saw something in writing. I never heard from him again.
John B, UK
My 82 year old mother has been the victim of these scams. Over the last five or six years she has spent all her captal and lost her luxury bungalow to these unscrupulous crooks. She is now living with me, her daughter and my husband. She is absolutely convinced that she is going to get her big win sometime soon and she cannot believe, despite our protestations that these people are thieves. She now has nothing left and is still getting between 20 and 40 letters per day, all junk mail. We have spoken to many many different organisations for help, all to no avail. Can no-one help these victims? We are at our wits end. No-one seems able or willing to bite the bullet and make the government change whatever legislation is necessary to stop these fraudsters.
Can you help???