The supplier is also banned from increasing vulnerable customers’ direct debits.

The regulator, Ofgem, said the ban will remain in place for three months unless the company significantly improves by:

• • Ensuring customer contact channels are improved, managed and maintained, with queries and issues being resolved in a timely manner;
  • Ensuring that the switching process is completed for customers, so switches go smoothly and are completed within the required timescales;
  • Ensuring that customers receive their contract renewal notice in a timely manner;
  • Managing complaints appropriately and resolving them in a timely manner;
  • Identifying vulnerable customers and ensuring they are receiving appropriate support;
  • Reviewing customer accounts (especially those in debt) to ensure customers in payment difficulty are managed properly, for example by putting them on repayment plans

Ofgem has sought improvements in Solarplicity’s customer service, which it said has been poor for a number of months.

Between March 2018 and September 2018, the regulator said there was an unacceptably high proportion of calls abandoned and unacceptably long call waiting times. While call handling has improved, Ofgem said it has not seen the required improvements elsewhere.

Mary Starks, executive director of consumers and markets at Ofgem, said: “We have taken action against Solarplicity to protect its customers from experiencing further detriment.

“Solarplicity must get its house in order and provide a level of service that its customers expect. If not, Ofgem will take the necessary steps to ensure customers are further protected and will take the relevant action needed to do this, which may result in its licence being revoked.”

Alex Neill, Which? managing director of home services, said: “Solarplicity finished rock bottom in our annual energy satisfaction survey, with scores of customers complaining about appalling customer service over the phone and online – so it’s right that the regulator is stepping in.

“As millions of energy customers brace themselves for yet another eye-watering set of price hikes, this should also serve as a warning to all firms letting their customers down with shoddy service, billing and payment problems or poor complaints handling that they need to up their game.

“Anyone unhappy with their current provider should look to switch to a better deal – and potentially save around £300.”