Consultants for the NDIS cost almost $30 million in just two years.

Despite the high spend, various advocacy groups still say the national scheme is falling behind and failing patients.

The National Disability Insurance Agency (NDIA) signed over 100 new contracts with external advisors in the two years leading up to its launch in July 2016, paying contractors $15.7 million in the 2015-16 financial year, and $12.3 million the previous year.

A series of reviews have been launched in recent years, including investigations of a computer system meltdown that ruined the NDIS's nationwide launch, its internal complaints procedure, and payments to disability service providers.

A spokesperson for the NDIA said consultants were brought in; “to respond flexibly to demand for different capabilities and to ensure a surge capacity”.

“The NDIA's operational costs are higher during the three-year transition of the scheme, reflective of the rollout of the NDIS nationally, and are within budget.”

Meanwhile, new complaints emerge, with the disability advocacy body First Voice saying support services for hearing impaired children are failing at a “rapid rate” due to underfunding.

“The long delay in … addressing the funding deficiency is precipitating market failure at a rapid rate,” First Voice chair Michael Forwood told a parliamentary inquiry this week.

“Service closures and reductions are already occurring, which will impact on participant choice and on children’s outcomes.”

He said the scheme had a faulty assessment mechanism which measures only observable impairment and disability, and so is liable to miss hidden hearing impairment in early infancy.

“The NDIA (National Disability Insurance Agency) do not understand hearing loss in children and they do not understand the basic principles of effective early intervention for children who are deaf and hearing impaired to put them on the path that they should be entitled to choose and enjoy,” Mr Forwood said.

Robbi Williams, the CEO of disability advocacy group JFA Purple Orange, says tight deadlines imposed by both the commonwealth and the states and territories are leading to less useful NDIS.

“The preoccupation with those markers places extraordinary pressure on the NDIA to hit numeric targets and, in so doing, to not have the fair opportunity to undertake an authentic, person-centred approach with each person in the scheme and their family,” Mr Williams said.

“We are concerned there is a yanking out of resource from existing services at state level that leaves families short.”