Consumers are being warned to be cautious about promotional deals containing cashback offers.
The Commerce Commission has received many complaints from customers who have had a lot of difficulty getting their cash back, particularly when they have bought computer equipment.
Under a cashback, a manufacturer promises to refund part of the purchase price for a product once certain conditions have been met.
The commission's director of fair trading, Adrian Sparrow, says a pattern is emerging, in which customers are finding that terms and conditions of the offer are forcing them to wait for months before receiving their refunds.
Mr Sparrow says though consumers must be conscious of the terms and conditions of the offers, retailers have a duty to ensure that the deals are honoured.
He says the commission will take enforcement action if it detects any breaches of the Fair Trading Act.