Contact Energy is warning of looming power price increases, saying current prices are unsustainable.
The company's annual profit has dropped 3%, as customers leave in droves in search of a better deal.
Consumer New Zealand says its powerswitch website has persuaded thousands of people to change companies.
Chief executive Sue Chetwin says many people have left Contact Energy for a cheaper supplier as a result of the campaign.
Ms Chetwin says the company is now trying to win back those customers with incentives including discounts for on time payments.
Contact Energy says it targets big power users, not small households, and expects prices will have to increase next year to be sustainable.
