Credit reference giant Equifax revealed in September that it had suffered a cyber data breach where 15.2 million records had been accessed.

Concerned customers took to the Equifax phoneline to seek help and advice, but many reported issues with the call service.

The Treasury Select Committee, chaired by Nicki Morgan MP, wrote to CEO Patricio Remon demanding an explanation.

In his response to the Committee, Remon said Equifax experienced some technical and operational problems with the helpline set up for those affected by the breach between 31 October and 4 November, but reassured MPs that the issues had now been resolved.

He stated Equifax suffered a short-term failure in its ‘telephony network configuration’ so some callers heard a busy tone, an incorrect pre-recorded message, or no ring tone at all. A small number also experienced poor quality phone connections.

Further, some consumers reported long waiting times to speak to a call centre agent. In the first and second week of posting letters to impacted customers (16 October onwards), Equifax received an average of 210 calls per day relating to the cybersecurity incident, with the average wait time at 20 seconds.

However, by the third week, an average of 2,145 calls were taken each day and Equifax said its call centre capacity failed to handle the higher-than-anticipated volume, meaning customers were on hold for five minutes, though a large number of calls were abandoned before being answered.

Remon wrote: “It has always been our priority to ensure impacted consumers receive the advice and protection they need. Unfortunately, we experienced some technical and operational problems with our telephone helpline. This is disappointing, and I recognise how frustrating this is for consumers.

“I sincerely apologise for any inconvenience caused. I am confident we have now resolved these issues.”

He added that to reduce the risk of any further problems, Equifax has quadrupled the number of phone lines, taken on an extra 130 call centre agents, opened a general enquiry helpline and updated its online FAQs.

Remon wrote: “I would like to assure the Committee that I am personally monitoring the situation and should any other problems emerge, I am committed to acting quickly and effectively.”