Thousands of customers were provided with an "unacceptable service" following Storm Arwen, which caused nearly one million homes in Britain to lose power, an energy watchdog said.
When Storm Arwen hit in November last year, of the one million households that experienced power cuts, 59,101 were without power for more than 48 hours and 3,032 for a week or more.
On Thursday 9 June, the regulator Ofgem published the findings of a six-month review into what went wrong and what the industry needs to change.
Akshay Kaul, director of networks for Ofgem, singled Northern Powergrid out as having the "worst" response among network operators.
Mr Kaul also issued a stern warning to operators ahead of any more extreme weather.
"My message to network companies this morning is really simple," he said. "They need to raise their game and get ready for the winter, and if we don't see the improvement that we're demanding, even tougher action is going to follow."
Northern Powergrid says improvements are already in motion and they were working hard to ensure customers were better supported.
Network operators have now agreed to pay a further £10 million in redress payments to communities on top of the £34 million already paid in compensation.
The report found some affected customers remained off power for an "unacceptable amount of time", received poor communication from their network operator and compensation payments took too long.
In 28% of cases, customers were given a restoration time that was not within 24 hours of their actual restoration time.
'Network companies need to do better'
Jonathan Brearley, chief executive of Ofgem, said: "It was unacceptable that nearly 4,000 homes in parts of England and Scotland were off power for over a week, often without accurate information as to when power would be restored.
"Network companies need to do better, not just to prevent power disruptions, but to ensure that when power is off, they work smarter to get people back on power quicker, and keep customers informed with accurate and timely information.
"This is the very least customers should be able to expect.
"The frequency of extreme weather events is only set to increase so it is really important that industry, and those involved more widely, learn from Storm Arwen to better respond in future."
Ofgem has published a list of 20 recommendations to ensure the scale of problems seen in the wake of Storm Arwen is not repeated in future.
'We will keep working to improve'
Northern Powergrid's chief executive, Phil Jones, has pledged to "play our part" in delivering the recommended improvements to "ensure the energy sector better supports customers in major power cuts and severe weather events".
He added: "We started to take action to improve our approach to customer communications and estimated restoration times during the later stages of the response to Storm Arwen, and we continued to work to improve that in the storms that followed.
"We have already seen some benefit from those early improvements that are helping to keep individuals, families, businesses and other key partners better updated and able to make more informed decisions in severe weather events. And we will keep working to improve – in line with the actions called for in the reports."
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