Crooks are pocketing thousands of pounds from a fraud in which they impersonate the police or a member of the victim's bank.
The scam, also known as courier fraud, exploits people who are often vulnerable or elderly, reports the charity Crimestoppers.
Victims have lost £5,000 on average, with £640,000 the highest single sum stolen.
The scam is hinged on there being an issue around a person's banking, and that without the victim's co-operation they, or their money, will be at risk.
Fraudsters often follow up by sending a courier to the target's home address to pick up their bank card, after creating a fake race against time to prevent any further scam, The Mirror reported.
The charity says criminals stole £15million using this type of con in 2021.
And sadly, in many cases, the victims oblige and are unable to claw back what they lost.
In 2021, more than 3,600 people fell prey to courier fraud, according to the National Fraud Intelligence Bureau (NFIB) - part of the City of London Police.
One victim was a woman in her 80s who was conned out of more than £30,000 after handing over her debit card and her driver's licence.
Now Crimestoppers is speaking out to draw attention to the fraud and the impact it has on individuals and families.
The charity also wants to gain vital information on the crime gangs behind the fraud and reach out to potential victims.
Crimestoppers is urging Brits to report courier scams to Action Fraud.
If a crime is in progress, the best thing to do is call 999.
The charity's director of operations Mick Duthie said: "Please help us stamp out courier fraud. If you know someone who is responsible but want to stay anonymous, tell our charity what you know.
"Call freephone 0800 555 111 or visit Crimestoppers-uk.org. Together, we can help protect potential future victims from being defrauded in this particularly horrible way."
Detective Chief Inspector Lee Parish, from the City of London Police, said: "Courier fraudsters prey on some of the most vulnerable and most trustworthy members of society.
"Just knowing how to spot the warning signs of courier fraud could be the difference on whether someone falls victim to these callous criminals."
The Government spent more than £100million investigating benefits fraud in the last three years, figures obtained by The Mirror reveal.
The figure would have been even higher, but during the worst of the pandemic many fraud investigators were roped into helping with huge increases in benefits claimants.
The definition of benefits fraud by the Department for Work and Pensions (DWP) is broad, and does not just cover people setting out to deceive.
It includes "someone obtaining state benefit they are not entitled to" as well as "deliberately failing to report a change in their personal circumstances".
A Freedom of Information request submitted by The Mirror found that the DWP spent £103.3million probing suspected welfare fraud from April 2019 until April 2022.
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