Grey Power is calling for greater Government regulation in the electricity industry after Mighty River Energy announced a record annual profit.
The electricity generator and retailer made $159.6 million in the year to June - a 43% increase on the previous year.
Its retail arm, Mercury Energy, has more than 350,000 customers nationwide.
Mighty River chief executive Doug Heffernan is defending the company's decision not to cut prices or give customers a rebate.
He says customers are already benefitting from a 12 month price freeze, which began in March, and the company did not ask them to top up profits when they fell in previous years.
Mighty River will pay the Government a dividend of $80 million, plus a special dividend of $150 million.
But Grey Power says its members have had to put up with rising electricity prices for years.
However, Energy Minister Gerry Brownlee says the profits Mighty River makes are going back to the people of New Zealand through the dividends the company pays the Government.