Customers were left in the cold, as energy suppliers refuse new applications

Ofgem, the energy regulator, requires suppliers to accept new customers, although there is no specific requirement that households must apply online.

However, Ofgem requires suppliers to make it easy for customers to compare tariffs. Ovo Energy was the only supplier that suggested prospective customers contact the company by phone to discuss tariffs after online applications were blocked.

An Ofgem spokesman said: “We expect authorized energy suppliers to welcome new customers when approached and ensure their connections are metered accordingly.

“Where this is not implemented, we will work with suppliers to ensure compliance with this requirement.”

The energy market has been changing this year, with competitive fixed-rate tariffs disappearing from the market in the middle surge wholesale prices.

Meanwhile, the price cap, which dictates the maximum amount suppliers can charge customers under their variable-rate tariffs, has risen sharply.

It was due to rise to £3,549 for the average household on the default tariff in October before the government took action earlier this month and guaranteed to stay at £2,500 for the next two years.