Consumers are increasingly falling victim to scammers posing as professionals from financial and legal services, Citizens Advice has warned.
The charity said it had seen a 6% increase in reports of these scams this financial year at a median loss to victims of £330.
They now accounted for a fifth of all scams reported to Citizens Advice's Consumer Service.
Reported cases of investment scams - such as those involving cryptocurrency, binary option investments and holiday timeshares - had doubled compared with last year, it said.
Victims have reported fake websites claiming to offer cryptocurrency investments like Bitcoin and pretending that household names have endorsed the company, scammers posing as stockbrokers who ask potential investors to place bets on whether phoney shares will rise or fall within a certain date, and criminals who promise to buy back timeshare memberships for an advanced fee.
Scammers have also posed as bogus solicitors, often striking during a property exchange and asking for the funds to be diverted to their bank account instead.
The charity is urging victims to "speak up" to break the stigma of what it believes is an under-reported crime.
Citizens Advice chief executive Gillian Guy said: "Fraudsters are using new technology to peddle old tricks, posing as trustworthy professionals with persuasive offers.
"Anyone can fall victim to these sophisticated scams, but all too often it's the victim rather than the scammer who is left feeling sheepish. This isn't right.
"So this year we want to break down the stigma around these serious crimes, which are targeted across all levels of society, yet remain under-reported."
Consumer minister Andrew Griffiths said: "Scams like these can have devastating financial and personal costs to those affected.
"Anyone can fall victim, young or old, which is why I am pleased to work with Citizens Advice to break the stigma and encourage people to speak up."
Martin Lewis, the founder of MoneySavingExpert.com who is currently suing Facebook for defamation after false adverts featuring him appeared on the site, said: "Scam ads have exploded across social media platforms over the last year.
"They look extremely professional and often use well-known faces to try and add legitimacy - the scum behind these ads are happy to target the vulnerable, unsuspecting or trusting. But they are sophisticated, anyone can be caught out."
Tips on how to avoid a scam:
- Be suspicious if you're contacted out of the blue, even if it's from a name you recognise.
- Don't be rushed - you never need to make a decision straight away.
- If it sounds too good to be true, it probably is.
- Be wary if you're asked to pay in an unusual way (such as vouchers).
- Never send money to someone you have never met.
- Never give out your bank details unless you are certain you can trust the person contacting you.
- Walk away from job ads that ask for money in advance.
- Genuine computer firms do not make unsolicited phone calls to help you fix your computer.
- Suspect a scam? Hang up, wait five minutes to clear the line or use another phone to call.
- Persuasive sales patter? Just say: "No thank you."
- Don't suffer in silence - speak out about scams.