NatWest has published the most common financial scams carried out against bank customers, as figures reveal that thousands are falling victim every year.
According to its records, nearly 7,000 people have been defrauded by scammers since the beginning of 2016.
Around a third of these cases involved goods failing to turn up, generally from online auctions and marketplaces. Customers, says NatWest, should always check the item description carefully and read the website's dispute resolution policy before buying.
It's also vitally important to use the website's official payment services, such as PayPal, and never be persuaded to pay via direct bank transfer away from the site.
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Another common scam is holiday fraud, which the City of London Police's National Fraud Intelligence Bureau says costs travellers more than £11 million a year.
In one recent case, a family of eight was left stranded in New York in freezing temperatures after the holiday apartment they'd booked turned out not to exist. In this case, they'd abided by app the payment rules and were given a refund and compensation by the holiday company concerned.
Family's New York holiday wrecked: apartment doesn't exist
Businesses are often also hit by financial scams, most notably invoice fraud. This happens when scammers send a bill that appears to be from an existing trading partner and that claims billing details have changed. This type of fraud, says NatWest, can cost customers an average of £30,000 a time.
"We know scammers can be convincing and they work round the clock to persuade their victims to part with money," Les Matheson, NatWest chief executive of personal and business banking, told a National Trading Standards conference in Westminster.
"We have hundreds of people working 24/7 to detect and stop fraud, but it's very important that, as individuals and businesses, we know how to protect ourselves."
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The top five scams facing NatWest customers
1. Goods not received
Customers pay for goods or services but never receive them from the seller.
2. Advance fee fraud
Fraudsters ask for an advance or up-front payment for goods, services and/or financial gains that never materialise.
3. Spoof payment requests
People receive a fraudulent request, purporting to be from someone senior in a company or a client, for payment or drawdown of funds.
4. Invoice fraud
Businesses are tricked into believing an invoice is from a trusted trading partner. The fraudsters claim that their payment information has changed and that money should be paid into a new account.
5. Holiday scam
Customers book a holiday, usually online, to find out later that the holiday doesn't exist.