Cumbria County Council are warning local business to be wary of cold callers offering tool sharpening services.
They say the traders usually offer to demonstrate their skills and provide an estimate before returning to take tools to be sharpened.
The council is warning that the traders make misleading claims with regards to how their prices are calculated and return days later with the tool, demanding thousands of pounds from the business.
When the businesses (which have included engineering and building firms) refuse to pay, they say the rogue traders then make aggressive demands for the money in person, by phone and email - causing serious disruption to the business.
The rogue traders are believed to frequently change their business name and telephone numbers, but maintain the same methods. The paperwork provided will appear legitimate, however the company is registered abroad.
For more information, or to make a report, you can contact the Trading Standards through the Citizens Advice Consumer Helpline on 03454040506 or you can contact Cumbria Police on 101.