Public confidence in power companies is still low, with customers rating them below Telecom and banks in terms of performance.
Despite having a "simple" task, electricity companies have huge variations in their performance records, according to the Consumers' Institute's customer satisfaction survey.
The biggest gripe is estimated accounts
being wide of the mark, leaving consumers with a nasty shock when they get their meter read and find they owe several hundred dollars more than they had budgeted.
"There's nothing difficult about electrons going down a wire. It's not like a motorcar with a whole lot of working parts that can go wrong," said Consumers' Institute chief David Russell.
The Institute canvassed more than 8000 electricity customers, and found that 66 per cent are pleased with their company's performance. But Empower and Genesis Energy languished around the 55 per cent mark, while Trustpower and Mercury Energy had above 70 per cent approval.
Russell said the results made shocking reading. "The energy company dealing with the customers - it's simply about getting the bill right. Estimated bills were the biggest bugbear for customers. They don't get the estimates right and there's no reason to get them so consistently wrong.
"Mistakes will happen but there just seem to be so many - it really does annoy a lot of people."
The website for the Electricity and Gas Commissioner lists billing complaints as 40 per cent of calls - the clear leader.
Jonathan Hill, spokesman for Empower, said he was surprised at the findings but would take the feedback on board.
"We are a bit surprised - our call centre is delivering very good service. But that's what the survey shows and we will take that on board."
However, few customers are likely to switch companies. Russell said that stemmed from the fear something would go wrong.
