The number of British Gas customers airing grievances about poor service standards has quadrupled in less than two years, according to Energywatch.
The consumer watchdog said that complaints against the UK's biggest utility firm went up from 20,072 between September 2005 and February 2006 to 80,541 between March 2007 and August 2007.
Further, Energywatch reported that British Gas was the worst- performing company in six out of seven service categories, including billing and complaint handling.
In total, British Gas accounted for nearly two-thirds of all complaints against utility companies received by the watchdog. This is a much higher proportion than can be explained by its overwhelming market share.
"The company is still in a league of its own when it comes to providing poor customer service," commented Graham Kerr of Energywatch.
"These new figures show that, compared with the best-performing company – Scottish and Southern Energy – British Gas customers are seven times more likely to need to come to Energywatch for help. BG has had a year to put things right and progress has been slow."
Npower received the second-highest number of complaints, with 13,960 between March and August 2007.