A woman was charged £1,000 to have a 20ft tree removed from her garden.

The work took just two hours and should have cost no more than £100.

The incident in Worthing was one of a number of rip-offs by cowboy workmen.

In Bognor, an elderly man was quoted £15 to clear gutters but the trader afterwards demanded £850.

The same trader returned and received a further £2,800 to repair roof damage caused by a bird's nest. Trading standards later found no work was needed or carried out.

Police today urged residents to be more cautious.

A spokeswoman said: "In addition to rogue traders, we have received a number of reports of offenders pretending to be antiques dealers, waterboard and gas officials.

"West Sussex trading standards and local police have been targeting these offenders during Operation Rat.

"Our rapid action team has received 18 calls in the last three months and our early intervention has saved consumers more than £20,000 - but residents are still being tricked.

"In Bognor, a trader laid a thin asphalt layer over a concrete drive for £1,250. Brick surround was laid loose and the finish was left so soft that cars sank into it."

The Office of Fair Trading estimates that 16,000 bogus trading cases are reported to them year and the cost to consumers often runs into thousands of pounds.

Lionard Barnard, West Sussex County Council cabinet member for public protection, said: "We are concerned for consumers tricked or pressurised into paying large sums for very shoddy goods or services."

He urged residents to keep front and back doors locked at all times.

Police advise householders to follow the SCC code to guard against bogus callers: Stop - Are you expecting anybody? Do they have an appointment?; Chain - Secure the door bar or chain before opening the door; Check - Ask for and double check the caller's identification credentials.

Home security advice can be obtained from police crime prevention officers on 0845 6070999.