An 84-year-old man in Horsham was almost duped out of several thousand pounds by rogue traders.
Two men visited the man at home, asking if he wanted his gutters cleaned and trees cut back, Sussex Police said.
The workmen quoted £460 but then changed the price to £5,850.
They left rubbish from their work and said they would come back the next day to clear it and get the money, according to police.
The unsuspecting resident went to his bank to withdraw £6000 for the work but suspicious bank staff raised the alarm about the cost of the work and contacted police, a spokesman added.
PC Bernadette Lawrie, BEM, financial abuse safeguarding officer at Sussex Police. said: “We urge residents to remain vigilant and to report anything suspicious to us.
“It’s also important to remember to challenge any unknown callers for ID.
“Not sure? Don’t open the door!
“Never have work done by anyone who cold calls. No reputable trader ever approaches a customer in this way.
“If visitors are present and you feel at all unsafe dial 999 at once. Otherwise report online or ring 101 quoting Operation Signature.”