Charges have been laid against Trustpower for its allegedly misleading offer of bundled electricity and broadband plans.
The Commerce Commission filed seven charges under the Fair Trading Act relating to Trustpower's television, online and billboard advertising between March and July 2015.
The advertising promoted a $49 a month for 12 months unlimited data broadband plan, under the campaign theme: "Good things happen when power and broadband get together".
The Commission said the $49 price was available only to customers who signed up for power and broadband at the same address on a 24 month contract term.
For the second 12 months the cost of broadband would be up to $79 a month and if a customer wished to cancel the contract at any time during the 24 month period they would incur exit fees.
The second year price was only disclosed in smaller print 'terms and conditions' at the foot of the advertising.
Trustpower indicated to the Commission that it intends to plead guilty to the charges.
In a statement, the power company said its plea was to expedite matters, and that it acted quickly to change its promotion when the commission raised its concerns.
"Trustpower is disappointed at the NZCC's (New Zealand Commerce Commission) decision to file charges, as the advertising was subject to external review and advice and Trustpower believed it was appropriate, but it acknowledges NZCC's views," it said.