According to rival-company figures, more than 10,000 customers left Contact after it increased power prices by 11% in November and raised its directors' fee pool in October.
TrustPower announced yesterday it had gained 7283 of Contact's customers in the past 10 weeks, 6058 of whom were from Dunedin.
Community relations manager Graeme Purches said he believed this showed competition was alive and well in the retail electricity sector.
"We have long said that while price is important, that is not usually the key reason most consumers choose to change suppliers.
"Our experience has been that it is usually dissatisfaction with the service they have received, or the fact that their supplier has simply upset them.
"In this case, it is a combination of all three, as consumers are certainly going to save money as well."
Meridian Energy had gained about 3700, spokesman Alan Seay said.
These customers had been gained "in the immediate aftermath" of Contact's announcement.
However, numbers had not changed much since then as, after a flurry of activity, reaction had "eased right off ", he said.
Mercury Energy had gained "thousands and thousands" of Contact customers, communications assistant Hannah Searle said.
"Consumers are really conscious of how they can make big savings by looking at their providers," she said.
The company was still seeing a consistent number of people swapping power providers.
Most people had initially switched because they were angry, but they were now switching because they were responding to advertising and using the Powerswitch.org.nz website to compare their bills, she said.
Contact communications manager Jonathan Hill said it was "no secret" the company had lost customers, and agreed with TrustPower's comments on the competitive nature of the market.
Despite the negative attention generated during the past few months, "the vast majority of our customers have stuck with us", he said.
Mr Hill expected customers to shop around, especially as other companies increased their prices.
