Operating profit at Npower fell €53 million in the six months to the end of June, down 60% on the period the previous year, and parent company RWE said the UK division would finish the year with a “significant deterioration” on the previous year. RWE said customer billing problems were a major factor – and one unlikely to be rectified until the end of next year – and a fall in customer numbers in both residential and business sectors. The company had been forced to offer residential customers with expiring contracts better conditions to retain them, the company said.