About 200 TrustPower customers have abandoned the company in favour of cheaper electricity since an advertising war broke out among three companies.
Energy Online and Powershop each launched advertising campaigns in Tauranga a month ago, which claimed TrustPower customers would be better off with them, despite the annual TECT cheque rebate.
TrustPower has since launched its own campaign in response and is preparing to lodge a formal complaint with the Commerce Commission and Advertising Standards Authority.
TrustPower community relations manager Graeme Purches said a total of about 200 of the Tauranga company's 59,000 customers had switched to other providers since the campaigns were launched.
"The churn has been really, really small," he said.