Impersonation scam cases more than doubled in the first half of 2021 to 33,115, a finance industry trade association has said.
This led to criminals stealing £129.4 million through this type of fraud alone, according to UK Finance.
In the same period last year, there were 14,947 impersonation scam cases which led to £57.9 million being stolen.
UK Finance raised the alarm at the start of Take Five Week (September 13 to 17).
The campaign urges people to stop to think, challenge requests from people, and protect themselves, for example by telling their bank and the police immediately, when asked for their information or money.
Impersonation scams involve criminals posing as a trusted organisation such as a bank, the police, a Government department or a service provider.
They trick their victim into transferring money using a range of cover stories. These include claiming they need to protect an account from fraud, that a fine or tax needs to be paid, or that a refund sent by mistake must be returned.
Politeness can sometimes get in the way of people refusing to speak to fraudsters.
Research for the Take Five to Stop Fraud campaign found nearly a fifth (19%) of people feel uncomfortable saying no to a request for personal information from a stranger via email or text, rising to nearly a quarter (23%) when it comes to phone calls.
Nine in 10 (92%) people admit to saying yes sometimes because they do not want to appear rude.
Using other phrases to avoid saying no, such as “Let me…