"We get regular complaints about the hard-sell and exploitative tactics these traders use," Consumer NZ chief executive Sue Chetwin said. "Many cases involve the elderly or vulnerable consumers, pressured to sign up for products they don't want and can't afford.
"We've dealt with cases involving elderly people sold $3000 vacuum cleaners that clean no better than vacuums you can buy for $100."
The stickers can be put on a letter box, front gate or front door.
"If a door-to-door seller ignores the sticker, they're likely to be trespassing," Ms Chetwin said.
Auckland University associate professor of law Joanna Manning said the sticker would cancel the implied entry licence for door-to-door sellers.
The householder could sue an errant trader for trespass, but if no damage was done then the courts might not award a big amount in compensation.
Consumer NZ wants the Government to change the Fair Trading Act to make it an offence for sellers to ignore a do-not-knock sticker. It says Australia's competition regulator last year took an energy retailer and its marketing company to court for ignoring such a sticker. The companies had to pay fines totalling A$60,000 ($67,445).
"We want similar penalties here to stop these traders."
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Commerce and Consumer Affairs Minister Paul Goldsmith said he would monitor the effect of the extended protections for consumers, which became law in June, before looking at new measures.
" ... [I] will consider other solutions if there remains evidence of a problem from door-knockers."
He said the new rules applied to all uninvited sales in the person's home, workplace and by telephone of $100 or more. Consumers have a five working day cooling-off period in which to cancel a purchase and get a full refund.
Genesis Energy announced in May it was quitting door-to-door sales. Meridian Energy said yesterday it wasn't doing door-to-door sales "and we don't plan to in the immediate future".
Consumer's chairman, Richard Aston, has put up one of the stickers at his Titirangi home. "It's a fantastic idea," he said. "My private space is invaluable. I don't want to be intruded on by people selling me things."
Door-to-door
What right do door-to-door sellers have to enter a property?
Everybody can enter a property and knock on the door if their purpose is lawful.
What is the effect of the 'Salespeople, Do Not Knock' sticker?
Its aim is to cancel the implied licence for all salespeople.
What can you do if a seller ignores the sticker?
Sue them for trespassing.
What might that achieve?
You might win the court case, but the damages award might not cover the legal costs.
Does the sticker apply to non-salespeople pushing ideas?
No, but Consumer NZ says that if you don't want politicians, market researchers or religious representatives at your door, you have the right to tell them to leave.
Where can the stickers be obtained?
From Consumer NZ and citizens advice bureaus. See consumer.org.nz for details.