One of the country's biggest power companies, Trustpower, has been fined $390,000 for false advertising.
Between March and July last year, Trustpower offered a 12-month unlimited data broadband plan at $49 a month.
But that price was only available to people who signed up for both power and broadband - and only on a 24-month contract.
For the second 12 months, the cost of broadband would rise to $79 a month, and any cancellation of the contract incurred a $195 exit fee.
The Commerce Commission argued the company's marketing campaign, which included TV ads and billboards, misled customers and kept important details hidden in small print.
During the campaign, 8000 people took up the offer.
In the Auckland District Court today Judge Rob Ronayne fined Trustpower $390,000.