ScottishPower customers are facing energy price hikes of up to 15% from this weekend.
The energy supplier, which has 5.2 million customers, says average dual fuel customers will see their bills increase by 14.8%, while electricity customers will see bills increase by 14% and gas customers by 15%.
The new prices will come into force from 2 February.
ScottishPower is the fourth big energy provider to announce price hikes, following in the footsteps of British Gas, npower and EDF Energy. It blames the increasing cost of coal and wholesale gas for the rises.
Willie MacDiarmid, director of energy retail at ScottishPower, says: "We have worked hard to protect our customers from these increases for as long as possible and offer consistently competitive energy prices.
“Our input costs are now at record levels, having increased by up to 97% since February 2007. Like other energy providers, we are now forced to pass on some of these higher costs.”
Some customers will receive some respite from the price hikes. ScottishPower says it will offset the impact of the increase for its Carefree Priority Services Register customers for the rest of winter, while eligible customers on its Priority Services Register can apply for a new Carefree Plus social tariff.
The supplier has also introduced a fixed price offer to shield customers from further increases until March 2017.
Joe Malinowski, founder of theenergyshop.com, says: “At the same time as this increase, ScottishPower has also pulled its highly competitive capped price tariff PriceFall. This leaves E.ON’s Price Protection 1 October 2009 as the best capped deal to go for.
"At an average cost of £904 for a customer paying by monthly direct debit it offers over 18 months of price protection at pre-increase levels. Customers who have recently been hit by a price increase should bag one of these deals before it also disappears.”
Earlier this week, an industry watchdog slammed energy firms for not taking customer complaints seriously.
Energywatch says it takes nearly seven months for energy suppliers to resolve customer complaints - leaving the vast majority of consumers unsatisfied.
It found that 97% of people who contacted its helpline between July and November 2007 thought suppliers failed to deliver on promises. The energy watchdog has now accused suppliers of not listening to customers, not returning calls and not updating accounts properly.
The research comes a month ahead of a report by regulator Ofgem into complaint handling standards by energy suppliers.
Allan Asher, chief executive officer of energywatch, says: “Energy companies are their own worst enemies. By not listening to consumers, not returning their calls, not updating accounts and many other examples that are signals of poor customer service, they give consumers no reason to stay.
“Worse still, they allow simple problems to turn into seven month sagas of broken promises and poor customer service.”
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