East Sussex Trading Standards issued the warning following a spate of cold callers offering house improvements or gardening services.
One resident was quoted more than £10,000 for replacement garage doors but was astute enough to turn down the offer.
Other services being offered include jet washing of driveways, removing moss from roofs, driveway resurfacing and offers to repair allegedly loose or damaged roof tiles.
Matthew Knowles, East Sussex County Council Trading Standards enforcement and investigations manager, said: “Bogus callers prey on the vulnerable, pressuring them into paying for work they don’t need for over-inflated prices.
“Our advice to people would be to never agree on the doorstep to have work carried out and don’t be tricked into thinking you’re getting a good deal in return for payment in cash or an immediate start to work.
“Always use a reputable trader, preferable someone who has been recommended by a friend or relative, take your time before making a decision and get several written quotes before agreeing to have any work done.”
Anyone who has concerns about doorstep callers is urged to call the police on 101, or the Citizen’s Advice Consumer Service on 03454 040506.