As part of its campaign, Consumer NZ is distributing free "Do Not Knock" stickers and is calling for changes to the Fair Trading Act to make it an offence for sellers to ignore the sign.
Mr Howard said some of the salespeople were unrelenting. He had experienced them and said many clients have fallen into the trap of buying from them and finding it a vicious cycle of debt: "They make it really hard for you. They are so persistent. They carry on and people feel pressured."
The "easiness" of credit and getting the product before fully paying was what enticed people - usually those who could ill afford it, Mr Howard said.
The salesmen sold everything from socks to electrical appliances, furniture and even power or DVD subscriptions with promises of easy payments.
"It's terrible and it's unethical ... it needs to be stopped," he said.
Mr Mackiewicz said it was criminal how some of the doorstep sales representatives tackled "vulnerable" people, talking them into buying expensive items they couldn't afford.
"People who can't get credit get to pay $10 down and after a payment or two they get the goods. Once they have paid them off or getting close to it [the salesmen] go back around and start hassling them to book up more ... It's not right. These people are having to go hungry to pay the bill ..."
Age Concern New Zealand also backs the Do Not Knock campaign. National chief executive Robyn Scott said older people often were pressured into buying on the doorstep.
"It is a huge concern that older people are being targeted, particularly vulnerable older people who may have dementia, be hard of hearing or are otherwise unable to recognise that they are being taken for a ride."
Meanwhile many Times-Age Facebook page followers who were asked about door-to-door salesmen said power companies were the worst. Many messages were posted on the page.
Tee Akuhata: yup shop direct home direct ect its annoying i just close the door on them they dont realize they are taking food outta kids mouths as they are very exspensive its better to layby.
Johanna Nightingale: Been there, done that. Be polite yet firm people ...
Kylee Puhara: Power companies, clothing trucks, movie companies. Worst thing is sometimes they keep coming back.
Dominique Parrant: Fatso whom I told no I don't want to sign up as I have quickflix bit they talked me into it by saying it was a free trial an I got 6 DVDs then got stuck with a massive bill for 2 DVDs ...
Caroline Jamieson: I got threatened by a power company for not following thru! Now i will never go with them!!