Genesis Energy has been strongly criticised by Energy Minister Gerry Brownlee for leaving hundreds of prepay customers "high and dry" without power at the weekend.
A software error meant people could not buy power on their prepay systems.
Genesis has 10,000 prepay clients but it was unclear how many were affected.
Mr Brownlee said it would be different if people had not paid.
"Where people are making every effort to pay for their energy...and can't because the metre somehow fouled up, then supply should not be cut at that point."
Genesis had "a bit of work to do to restore integrity in the scheme".
"I'm extremely disappointed and annoyed that these people have been left high and dry like this," Mr Brownlee said.
It would be up to the shareholding ministers to approach Genesis about the issue.
Genesis said the system was up and running by Sunday afternoon.
Consumer watchdogs are calling for Genesis to pay compensation to affected customers.
- NZPA
Brownlee slams Genesis for power glitch
AdvertisementAdvertise with NZME.