The company no longer has the correct addresses for many of those due cash, prompting fears they many never see it.
Christine Farnish, of Consumer Focus, says: "We want to encourage all those consumers still entitled to a refund to get the cash that's rightfully theirs."
It may provide a particularly rare opportunity for customers to stand to gain financially from a transaction with a dual fuel provider, so many will be eager to take it.
The Scotsman recently told how families in Scotland are set to be an average of £112 worse off after National Insurance and VAT rises – a sum that could be covered by the npower refund.
Posted by Richard Eden
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