UK energy regulator Ofgem has said it will impose a fine of £10.5m on utility giant SSE for prolonged and extensive mis-selling of gas and electricity over two years.
The fine is the largest ever imposed on an energy supplier by the watchdog.
Ofgem said in a press statement that SSE breached its obligations relating to telephone, in-store and doorstep sales activities between 2009 and 2011.
"In particular, SSE consistently failed, over a prolonged period of time, to conduct its sales activities in a way that would provide clear and accurate information on prices and potential savings to enable customers to make an informed decision about whether to switch suppliers, " the watchdog added.
Ofgem senior partner in charge of enforcement Sarah Harrison said in order to restore trust in the energy market, suppliers must comply with the obligations and "play it straight" with consumers.
Energy Minister Michael Fallon said of the news: "I have rarely seen a worse case of consumers being misled so badly. With rising energy prices, and multiple tariffs to contend with, consumers deserve the clearest, fairest and best possible deal."
SSE said that it is "deeply regretful" of the breaches and apologises "unreservedly" to any customers who have been affected by sales activity, which ran counter to the values and culture of the company.
SSE managing director of retail William Morris said: "During the period in question we worked hard to offer competitive prices and carve out an industry-leading position on customer service."
"We did not, however, spend enough time monitoring our sales processes. That meant we did not always sell in the right way, and we let some customers down," Morris added.
In July 2009, Ofgem imposed a £2m fine on EDF for providing a "poor service" to homes and businesses in London.
Image: Ofgem says SSE misled their customers about gas prices. Photo: Courtesy of FreeDigitialPhotos.net.