Grey Power wants people to bombard politicians with letters demanding that power companies repay six years of overcharging, amounting to $4.3 billion.
After a four-year inquiry, the Commerce Commission issued a finding on 21 May that Contact Energy, Genesis, Meridian Energy and Mighty River Power used their market power to increase earnings by this amount from 2001 - 2007.
Grey Power says electricity customers were "ripped off" over six years and it's time to give the money back to consumers.
The lobby group is using its network of about 80 organisations to rally its members to put pressure on politicians to obtain some compensation.
Campaign organiser Errol Miller says a last resort would be for Grey Power to march on Parliament if the Government does not listen to its 83,000 members.
The Minister of Energy expects a technical advisory group to report on electricity sector reform by September.