Former customers of failed energy supplier Utility Point have been left frustrated over what will happen to their account balances as households prepare to turn the heating on for winter.
Utility Point and People’s Energy ceased trading on Tuesday in a move that affects half a million customers in the UK.
However, some say they had up to £600 in credit with the company at the time of its collapse.
Energy watchdog Ofgem will now decide which firm to switch thousands of customers over to.
Utility Point has around 220,000 customers while People's Energy has 350,000 people signed up to its services.
One Utility Point customer is Danielle Brighton, 27.
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She told The Mirror: "I am so unhappy that this has happened because I'm left in limbo.
"I found out due to an email from Look At My Bills, the comparison site that I go through for my gas and electric."
Brighton said she expected some sort of warning this would happen and for it not to be such an unpleasant surprise.
Any credit is meant to be swapped over to whichever energy firm takes over from Utility Point.
But Brighton said she can't even log into her account to see what her credit balance is, so has to trust she isn't "losing out on money that I am owed".
"This is an extremely worrying time and with the switch over we don't know if we are going to be better off or worse off with the new provider and whether we will get a better deal," she added.
"As first-time homebuyers we are very limited on money and this is not something we needed at this current time."
Another Utility Point customer, Gareth, from Wigan, said the energy firm let him renew his deal just three days before it stopped trading.
He said: "They are also sitting on a credit balance, whilst albeit small it is still my money and not theirs.
"With prices already rocketing up, I am now worried that a change in supplier in the midnight hour, which I have no initial control over, will leave me out of pocket.
"And with less options on the market now, what will happen to prices overall if competition between the energy suppliers keeps reducing?"
A Mirror reader who preferred to stay anonymous said: "I'm concerned as I am approximately £600 in credit and can't get in touch with anyone to find out what is happening."
Utility Point has been approached for comment
A statement on the Utility Point website said: "It is with regret that we must announce that Utility Point is ceasing to trade.
"Customers need not worry, their supplies are secure and domestic credit balances are protected."
It comes after both PFP Energy and MoneyPlus Energy ceased to trade last week with nearly 90,000 energy customers left waiting for a new supplier.
Green Network Energy and Simplicity Energy also collapsed in January this year, affecting 400,000 households.
If you're a Utility Point or People's Energy customer, the current advice from Ofgem is to sit tight and wait until your new supplier contacts you.