Npower, a leading energy firm, will pay a total of about £3.5 million to vulnerable customers after it was discovered that the company breached energy sales rules in the country.

UK's regulator, Ofgem said that the company's failure to ensure that doorstep and telesales staff kept customers informed. The regulator said that this prevented the customers form making information decisions about whether to change suppliers. The company has addressed the shortcomings by September 2012 and now agreed to pay at least £25 to each of its customers who receive the Warm Home Discount.

The regulator said that npower had incomplete information about customer's consumption preventing them from making informed decisions about changing energy suppliers. The company also did not make sure that comparisons between the price of npower's supply and that of the customer's current supplier were based on tariffs being charged to the customers. Npower will write a letter to the customers who are affected due to the breach.

Paul Massara, npower's chief executive, said, "It's good to draw a line under this, so we can focus on our goal of becoming number one for customer experience by the end of 2015."