Energy supplier SSE has revealed it lost another 230,000 customer accounts as households continued to switch away from the Big Six to cheaper rivals.
SSE blamed a "highly competitive" market after total customer accounts in the UK and Ireland dropped to 7.77 million in its first quarter to the end of June from 8 million a year earlier.
The fall came after it shed 210,000 accounts in the previous year to the end of March.
SSE, which raised dual fuel prices by 6.9% on April 28, said it also came under pressure in the first quarter as the warmer weather saw households use less gas and electricity.
The group said the average temperature in the UK over its first quarter was 0.9C warmer than a year earlier after Britons sweltered in the hottest June since 1976.
Alistair Phillips-Davies, chief executive of SSE, said: "As expected, 2017/18 is presenting a number of complex challenges to manage."
The Government has watered down its election pledge to knock £100 off energy bills for households through a price cap, with regulator Ofgem instead consulting on a proposed "safeguard tariff" for vulnerable customers.
In its latest update, SSE said: "Competition should be at the heart of the retail energy market and in line with that promotes a range of tariffs, products and services."