Serious complaints against door-to-door sellers has led Consumer NZ to launch a nationwide campaign against the sales tactic.
Chief executive Sue Chetwin said Consumer received regular complaints about "hard-sell" door-to-door sellers.
"We get regular complaints about the hard-sell and exploitative sales tactics these traders use. Many cases involve elderly or vulnerable consumers, pressured to sign up for products they don't want and can't afford," Ms Chetwin said.
"We've dealt with cases involving elderly people sold $3000 vacuum cleaners that clean no better than vacuums you can buy for $100. We've also dealt with complaints from consumers pressured to buy grossly overpriced beds and other household goods they couldn't afford and had to go into debt to purchase," she said.
As part of its campaign, Consumer is distributing free "Do Not Knock" stickers and calling for changes to the Fair Trading Act to make it an offence for sellers to ignore the sign.
"We're encouraging people who don't want door-to-door sellers to knock to put a sticker on their letterbox, front gate or front door," Ms Chetwin said.
Everybody had an implied licence to enter a property and knock on the door.
But people could revoke a salesperson's licence to enter their property by displaying a "Do Not Knock" sticker. If a door-to-door seller ignored the sticker, they're likely to be trespassing, she said.
Consumer is also calling for changes to the Fair Trading Act to make it an offence for sellers to ignore a "Do Not Knock" sign.
Door-to-door sellers in Australia can be fined if they ignore a "Do Not Knock" sticker. Ms Chetwin said Consumer wants to see a similar law change here.
A recent Consumer NZ survey found 70 per cent of its members disliked door-to-door sellers and wanted them to stop calling. More than 60 per cent dubbed these traders "annoying" and "intrusive".
Survey respondents also complained of pushy door-to-door sellers who wouldn't take "no" for an answer. Several members said they had to threaten to call the police to get the salesperson to leave.
How to get a "Do Not Knock" sticker:
* Pick up the November issue of Consumer magazine available from 10 November: a "Do Not Knock" sticker is included free with the magazine.
* Send a stamped, self-addressed envelope to: Do Not Knock, Consumer NZ, Private Bag 6996, Wellington 6141.
* Visit your local Citizens Advice Bureau: Consumer is distributing "Do Not Knock" stickers through the Citizens Advice Bureau and other organisations that want to support the campaign.