EE has recalled all power bars and have offered customers a £20 voucher in exchange.
The free power bars were offered to customers to help with charging on-the-go and the Barnsley EE store in the Alhambra were inundated with customers collecting them when they launched.
But in a statement published yesterday EE revealed all are being recalled as a precaution.
The statement added: "This is just a precaution, but we want to make sure all our customers are safe.
"If you have a Power Bar, you should stop using it straight away and hand it in to one of our stores.
"We are taking this action because we are aware of a very small number of further incidents where Power Bars have overheated in circumstances that could cause a fire safety risk."
Customers who return the power bar to stores will get a £20 voucher if they are an eligible EE customer.