It looks like energy customers won’t be sending their suppliers many Valentine’s cards this year – but there may be plenty of complaints.

Not after new figures show the Big Six energy companies received more than 5.5 million complaints in 2013.

The giant volume of complaints ranged from issues with bills, metering, customer service and switching through to payment.

EDF had the highest proportion of complaints – with more than 80 per 1,0000 customers, compared with the best performers ScottishPower and SSE which had roughly 14 per 1,000 apiece.

But npower got the most overall, with 1,383,650 complaints pouring in, closely followed again by EDF with 1,240,005 and British Gas with 1,235,550.

E.ON narrowly avoided the million mark with 929,230 while the two Scottish companies each had less than 500,000.

Consumer watchdog Which? is calling for the “broken” energy market to be fixed after its latest survey found eight in 10 are worried about rising energy prices. Just one in five trust gas and electricity suppliers.

The group’s Executive Director Richard Lloyd said: “Next month we want the regulators to refer the energy market to the Competition and Markets Authority and launch a full scale inquiry. This is the first and most important step towards a more radical reform of the energy market, giving hard-pressed consumers the confidence that they are paying a fair price.”

Appropriately for the date, the trade body for power suppliers, Energy UK, said its members are now putting customer service at the “heart” of what they do.

A statement said: “No industry wants unhappy customers but when you are dealing with nearly 27 million customers things can occasionally go wrong.

“They [the energy companies] are making it easier to compare and find the best deal available – most recent figures show that around 1.3 million customers switched in the last quarter of 2013 alone.”

The Big Six suppliers now supply 97% of domestic customers – until recently they held 99% of the market.