Genesis Energy has rejected criticism that it acted despicably when electricity prices spiked last Saturday.
The publicly owned energy generator and retailer says it did nothing wrong when it charged $20,000 a megawatt-hour during a planned maintenance shutdown on the national grid.
Meridian and Mighty River Power say that's four times the price they've paid in the past, and the Electricity Authority is investigating.
For Genesis, Richard Gordon says the price reflects the cost of firing up the Huntly power station, and all participants had the chance to buy power beforehand at much cheaper prices.
"We offered hedges as late as three o'clock on Friday afternoon," Mr Gordon says, "and they chose to not manage their risk."