A MARTIN Lewis fan has shared how they managed to claim back £600 within days.
Lewis' MoneySavingExpert blog has revealed a quick tip to see if you are due cash in energy direct debit.
According to the money expert, energy firms could be building up a reservoir of over £3billion in customer cash.
The energy providers are sitting on the extra money unnecessarily while households are unaware that they can claim it back.
If you pay your energy bills through direct monthly debit, you could be owed a refund.
Ideally, you should have little energy credit or be a month in energy debt by May.
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But if you have a lot of credit during summer, you could ask for it back by calling your supplier.
Your energy provider will be obliged to refund it, or clearly explain why not.
One fan followed the advice and proved successful as she claimed £600 back.
She wrote: "I got in touch with my supplier Utility Warehouse, as I was £600 in credit. Asked for it to be refunded - no issues at all.
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"Money was in my back account within four days."
Usually, the energy provider calculates your yearly energy costs and divides them into 12 equal installments.
Customers are more inclined to accumulate credit during the warmer summer months in order to even things out over time and prevent hefty bill shocks in the winter.
But these estimates could be wrong if you don't give regular meter readings or have a smart meter at home.
Some customers could be left overpaying while others get into too much debt.
Lewis said: "We're meant to be in credit for part of the year, debt for the rest - the key's to know where you should be at, when!"
If you've got credit on your account, you have every right to get it back - although some experts recommend keeping it there through the summer, so your bills don't go up in the winter when you use more energy.
How can I request a credit refund?
First, make sure your energy firm has the most up-to-date meter reading.
If your reading doesn't match the energy use they have down for you, chances are they'll want to update your monthly bills as you may not be paying the right amount anyway.
But if your meter readings are up-to-date and f you've been in credit for more than one month ask your energy firm to return the funds.
Each energy supplier has its own process for customers wishing to get a credit refund.
After submitting a meter reading to your online account customers should head to the payments page and click apply for a refund.
Check with your energy provider to find out how to request your money back.
Lewis has previously shared two helpful tips that could help you claim back thousands of pounds.
The founder of MoneySavingExpert is encouraging households to “check and challenge” their council tax band.
He has also revealed how switching current accounts could land you with a quick £175 cash boost.
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Another fan used Lewis' trick to bag £575 in free cash and a free holiday.
Meanwhile, 500,000 households have been urged to make a simple check to see if they can get £4,000 free cash help.