Lobby group Age Concern says people will die unless urgent action is taken on energy poverty.
A Commerce Commission report last week said Meridian Energy, Contact, Genesis and Mighty River Power earned $4.3 billion more than they should have done between 2001 and 2007, because of a lack of competition.
Age Concern has since written to the Government requesting a full investigation into electricity retail costs and prices.
It also wants State Owned Enterprises in the electricity sector to make an annual contribution of part of their surpluses, to insulate homes for improved energy efficiency.
Age Concern president Liz Baxendine says the profits earned should be used to undo some of the harm she says has been done by high electricity prices.
She says a programme of emergency payments and rebates is needed to help low income and vulnerable people during winter.