There's some doubt over whether power companies will play along with new guidelines. 

Last year it was revealed some Meridian Energy customers were being charged 11 percent more than the price shown on a comparison website.

The Electricity Authority is set to roll out new guidelines - discouraging the practice of charging some people more than others for the same service.

Consumer New Zealand's Jessica Wilson told Mike Hosking retailers structure their plans to make it difficult for consumers to get a better deal. 

"Retailers introduce new plans, make those offers available to new customers, but keep their loyal customers on a pricey tariff and just sit there taking in the money."

She says retailers have deliberately made the market tricky to navigate.

"Retailers have been raking in millions of dollars a year from customers being on a more expensive tariff then they need to be, and those estimates are $39 million each years - so that's alot of dosh."

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