The regulator will look at the estimates supplied to customers about how much energy they used in the winter of 2016/17.

Ofgem will also investigate the accuracy of the annual consumption figures provided to customers in their annual statements.

Incorrect consumption figures mean customers receive inaccurate bills and annual statements, which in turn can lead to them being unable to manage their accounts and not being properly informed when choosing to switch supplier.

Ofgem added that by opening this investigation, it is not implying that it has made any findings about non-compliance.

Ovo Energy was founded in 2009 and has nearly 800,000 customers, representing a 2.85% share of the UK retail energy market.

An Ovo Energy spokesperson, said: “We have a great track record in customer service and are always open to ways to improve it.”