Rogue traders have conned almost £100,000 from Westcountry homeowners this year – almost double the total two years ago – it has been warned.
Council trading standards teams in Devon and Torbay said they had seen an increase in complaints from residents about cold callers.
In Devon alone a little over £50,000 was reported to be lost to doorstep crime in 2010. This year it is already almost £100,000.
It's thought only a tiny percentage of doorstep crime is ever reported with victims being too frightened or embarrassed to come forward.
Paul Thomas, chairman of the Trading Standards Partnership South West, said: "Doorstep criminals operating across the region will often go door to door persuading residents to have home building and maintenance work done, so it is important that we work with our neighbours to investigate reports and share intelligence.
"Through years of partnership working we have built up a powerful network of professional experience and expertise.
"Rogue traders should be aware that trading standards and Scambuster teams across the South West are working closely together and with the police, to crack down on doorstep crime.
"The figures we have on reported incidents of doorstep crime in the Westcountry are just the tip of iceberg.
"We need people to let us know if they have been a victim of doorstep crime, as higher levels of reporting mean we will gain intelligence to drive out this kind of activity.
"Doorstep crime of any kind is totally unacceptable and often has a real impact on the victim's sense of confidence and security in their own home. Rest assured that we will continue to work together to identify those involved, and bring them before the courts."
In the Westcountry the most common complaints are in relation to household maintenance work, such as gardening, driveway work and roof repairs, with victims tending to be elderly and vulnerable.
Residents have suffered poor, and sometimes dangerous workmanship, unfinished work, being charged for work not completed and threatening and aggressive behaviour.
The warning was issued as part of a national campaign to encourage people to say no to cold callers got under way.
Trading Standards Institute's annual consumer week – under the banner "Cold calling – Don't Buy It!" – is aiming to raise awareness about the issue of rogue traders and the fact that refusing to leave someone's doorstep when asked is a criminal offence.
It said consumers who need guidance on their rights or want to report a dodgy cold caller to trading standards should call the Citizens Advice consumer service on 08454 040506.