The costs of introducing a new computer system to Scottish helpline NHS 24 have now risen to 73% more than was originally budgeted, according to the country’s official auditors.

Audit Scotland says that every month the Future Programme project is not operational, NHS 24 is incurring another £500,000 in additional costs.

The programme was launched in 2009, and awarded contracts to Capgemini and BT to modernise its telephone and IT systems two years later. The programme ran into a series of delays, which prompted the threat and then the withdrawal of legal action against Capgemini.

The system finally went live in October 2015, more than two years later than originally planned, but crashed immediately. NHS 24 then had to revert to its old IT system.

The helpline made another attempt to get its new system live on 3 November 2015. But it switched it off again after six days, because staff were struggling with it so much that call times had doubled.

Testing in April this year showed the system was still not ready to go live. “Failure to launch successfully, and additional double running costs, have meant that NHS 24 now estimates the total projected cost of the programme will be £131.2 million, 73% above the £75.8 million included in the original business case,” the Audit Scotland report concludes.

The special health board agreed a loan with the Scottish government to cover the additional costs of the programme, on the basis that it would get its new IT system live in June. This did not happen, so the brokerage has been extended by two years.

Despite this, the auditors say NHS 24 is struggling to make the efficiency savings required of it. Improving efficiency was one of the reasons for launching the Future Programme, which was supposed to generate savings of £10 million over ten years.

NHS 24’s board now has a revised, three stage implementation plan in place. This should see the planned care services element of the project go live this autumn. Unscheduled care services, which covers individuals and families who need advice out of hours, will go live in one NHS board area next March.

The service should be available in all board areas by the end of December 2017 – four and a half years later than originally planned.

Alongside the roll-out, NHS 24 is planning to introduce six specific helpline services for depression, CBT, joint problems, death certification, blood donation, and getting fit for work; which won’t rely on the troubled IT service’s algorithms.

Audit Scotland concludes: “The board has taken a fundamental look at what needs to be addressed in order to fully implement the new system. While significant challenges still remain, the board is now taking reasonable steps to mitigate the risk of further delay.

“Delivery of financial targets will be very challenging, and will largely depend on achieving efficiency savings.”

In a statement, NHS 24 chief executive Angiolina Foster, said it “acknowledged” the findings but remained confident that the new IT system would eventually enable the development of “new and improved” services to Scotland.