Rogue traders have conned almost £100,000 out of Westcountry homeowners this year with elderly and vulnerable people among their main targets.
The figure is almost double the total two years ago and it has been warned that this is just the "tip of the iceberg".
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.
Paul Thomas, chairman of the Trading Standards Partnership South West, said: "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."