Advocates fear the National Disability Insurance Scheme risks entrenching disadvantage, with rich people able to access better levels of care.
A parliamentary inquiry into the scheme has heard bureaucratic language, long waiting times and a general lack of knowledge of disabilities by government staff were creating serious problems.
One advocate, Kirsten Deane from Every Australian Counts, came close to tears when she gave evidence in Brisbane on Tuesday.
Ms Deane is furious about a $4.6 billion federal government underspend on the NDIS.
"We don't find anything to celebrate in the underspend at all, that is money that is desperately needed," Ms Deane told committee members.
The government blames the funding disparity on a slower than expected uptake.
But Ms Deane puts it down to approval delays, long waits for services, and inappropriate plans, meaning people aren't spending the money allocated.
She spoke of one child who died while waiting for support, but did not elaborate.
Ms Deane said there was an increasing worry that the system was becoming "dual track", with people from indigenous, ethnic or lower-socio economic backgrounds unable to navigate the system.
"If we don't do something ... we're going to end up entrenching disadvantage," Ms Deane said.
Deaf Services told the committee hearing impaired people were being told to watch YouTube videos to learn sign language, and faced barriers accessing basic forms because it meant picking up the phone.
Michelle Crozier said her clients were being told by insurance planners that they had never met a deaf person, reducing confidence they would get an appropriate plan.
Representatives from the AEIOU Foundation, an early intervention group for children with autism, said staff helping dole out NDIS plans needed to be better listeners and more empathetic.
The committee heard social workers, counsellors or therapists would be better placed to help people access the scheme.
Assistive technology supplier Tiffany Heddes said NDIS planners simply did not understand the equipment.
"We've had instances where planners have phoned our company to explain the difference between a walker and a standing frame," Ms Heddes said.
Earlier, Ms Deane was joined by advocate Peter Tully, who said people were asked personal questions by agency staff they had just met.
Some clients were unable to afford assessments by independent groups to prove they had a disability.
The committee is looking into various aspects of the NDIS, including its performance and governance, as well as support for people receiving in-home care.
Australian Associated Press