It will look at whether the supplier breached any rules relating to the way it treated customers and whether those in debt were given “appropriate” repayment options.

As such, Ofgem will investigate whether Utility Warehouse does enough to try and contact customers in or at risk of debt and if manageable repayment plans based on their ability to pay are offered.

Another area it will look at is whether pre-payment meters are being installed appropriately as a means of recovering debt from customers, especially when they’re installed as a last resort.

Ofgem added that in opening this investigation, this doesn’t imply there has been any non-compliance by Utility Warehouse.

A Utility Warehouse spokesperson, said: “We are surprised and disappointed that Ofgem has decided to launch a formal investigation into some of our processes.

“Ofgem requested an independent audit of our indebted customer processes towards the end of 2017 which PWC undertook. This provided an overall positive report, with a number of best practice recommendations now having been implemented.

“The Ofgem statement specifically states that while it is opening an investigation it does not imply there has been non-compliance by Utility Warehouse.”