The energy regulator said 90,000 Iresa customers will be moved to Octopus Energy, which will honour all outstanding credit balances. This includes money owed to both current customers and to past customers of Iresa.

The news comes after it emerged on Friday that Iresa Energy had ceased trading a month after it faced an extension on a ban to take on new customers after failing to resolve service issues.

Greg Jackson, CEO of Octopus Energy, said: “We are delighted to welcome Iresa’s customers to Octopus, and we will work hard to be a safe haven after the terrible experience they have had.

“Iresa’s records are in a terrible mess, so it will take us a bit of time to untangle them. Customers should take a meter reading as soon as possible, and wait to hear from us once we’ve transferred them to our systems.”

Our Q&A explains what happens next:

What tariff will I be put on?

Former Iresa customers will go onto the ‘Flexible Octopus’ tariff, which Ofgem said is “one of the most competitive tariffs on the market and the best value deal on offer for customers”. Octopus confirms the annual price for average energy users stands at £955.

Can I switch provider?

Ofgem urges customers to sit tight and wait until Octopus contacts them by Tuesday 14 August. The switch from Iresa to Octopus will take around a week. If you decide to switch supplier before Octopus has completed the transfer, it may take longer to complete as it will be seen as two switches taking place.

Once the transfer has taken place and you want to switch, you need to ask Octopus to move you to another deal, or you can switch to another provider. You won’t be charged any exit penalties.

I had a credit on my account, what happens?

For current customers, any credit on their account can be used to offset future energy use. If you’re a former customer, Octopus Energy will get in touch directly about a refund.

I owe Iresa money, what happens?

If you owe money or are in debt to Iresa, you will not need to pay the balance to Octopus Energy. Instead, Iresa administrators will be in touch with you to set up a repayment plan.

What should I do about my direct debit?

If you paid your energy by direct debit to Iresa, don’t cancel it. The direct debit will be transferred to Octopus Energy to start taking payments and the supplier will contact you shortly to explain how they will set up your account.

What’s Octopus’ Energy customer service like?

Ofgem said Octopus had a good customer service record, with a 3.8 star rating out of 5 in the Citizens Advice league table. It’s also a Which? Recommended provider for energy. It currently has around 250,000 customer accounts.

I have more questions, who should I contact?

Customers with questions should contact Octopus Energy’s customer service team, on 0808 1781551 or iresa@octopus.energy