Rogue traders are fleecing the elderly hundreds of times every day, according to the Trading Standards Institute (TSI).
In a campaign starting this week, the organisation is calling on people to look out for their neighbours and help protect them from the con men.
"Trading standards officers and police forces do an excellent job stamping out doorstep crime," says TSI chief executive Leon Livermore.
"However, we need citizens to help prevent doorstep crime from taking place in the first instance in order to prevent far-reaching detriment from taking hold of an individual's life, and to prove to rogue traders that Britain's communities are out of bounds for their unscrupulous activities."
Every year, says the institute, rogue traders rip off a pensioner around 169,000 times, convincing them to pay for shoddy or incomplete repair work, charging extortionate fees for their services, or threatening people that don't comply.
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Andrew Millar, aged 86, who had more than £157,000 stolen, explained that the gang had built up trust over a long period and discouraged him from speaking to friends or relatives.
"Doorstep crime affects the most vulnerable people in society leaving them distressed, scared and thousands of pounds out of pocket," says consumer minister Jo Swinson. "We must do everything we can to keep rogue traders from their door."
So what should good neighbours look out for?
Traders cold calling in the area
Builders' vans parked nearby - particularly those that don't include a company name or contact details
A sudden start to building or maintenance work on your neighbour's garden or house
Poor quality work visible on the roof, driveway, or property
Your neighbour appearing anxious or distressed
Your neighbour visiting the bank, building society, or post office more frequently, particularly in the company of a trader.
And how can you help?
Ask your neighbour in private if things are OK
If they're unhappy, suggest calling a relative or carer on their behalf
Make a note of any vehicle registration numbers
Keep hold of any flyers you've received through your door
Ask your neighbour if the trader has left any paperwork, and put it in a clean food bag
If you suspect a crime is being committed, call the Citizens Advice consumer helpline on 03454 040506 or contact your local trading standards office
If the situation with the trader starts to look volatile, call the police.
Read more about rogue traders on AOL Money:
Jail for gang of rogue builders
Rogue traders cash in on recession
Bid to drive rogues out of business