Dealing with post-traumatic stress disorder from a childhood of abuse and carer to someone with a psychosocial disability, she struggled alone, without support before the scheme came along.

"I felt relief and optimism for our future," she told a parliamentary inquiry on Thursday.

Instead, the National Disability Insurance Scheme took on the role her childhood abuser once played. It would pop up at times and attack unexpectedly.

One stroke of a pen from a bureaucrat she'd never met was the difference between her family having a good or bad year.

While she wasn't allowed to have a single point of contact or direct email, she was expected to jump every time the agency rang from a private number.

Where she was bound to meet deadlines, the agency was under no such compulsion. Ms Warn waited 10 months for a light touch review to even be acknowledged.

Staff questioned her every last decision. She had to fight for every dollar allocated. Money that wasn't spent was removed from subsequent plans.

The stakes were high. One wrong move and funding would be revoked. The threat of having her self-managed status stripped away at any time hung over her.

"Far from my original hopes, the NDIS is a risk to my health. It's unsustainable for me to stay in the system," Ms Warn said.

"It wielded power over me that made me feel helpless."

Social worker Michel Hansen said Ms Warn was the rule, not the exception when it came to NDIS participants in Canberra.

Even though the ACT was one of the trial sites for the scheme it was one of the most "poorly acting" in her opinion.

One local area coordinator has refused to acknowledge her client is mentally ill and thus eligible for the NDIS, even though the woman had just spent two years in a mental health unit.

Children who needed an hour each week of physio, occupational therapy and speech therapy separately were being given an hour for all three services.

Another client with a rare disability which included blindness, a hearing impairment and muscle degeneration was having trouble getting the NDIA to acknowledge the two latter conditions.

"My clients are great, but I am just sick of fighting to get them the basics," Ms Hansen said.

"I don't even care about above basic anymore. If I can get him a basic decent plan, I think that's a victory, whether it meets their needs 100 per cent.

"I've given up thinking that a plan will be given that will meet 100 per cent of the clients' needs now, I'm happy if I get 60 to 70 per cent meeting their needs. It's just not happening here in the ACT."

Ageing parents of adult children with disabilities said they feared there would be no one to fight for their child when they were gone.

Karna O'Dea, whose children aged 19 and 32 have severe autism, said the agency needed to sort out what do do in those cases.

"The NDIS is going to have to loco parentis to some of these people," Ms O'Dea said.

There also needed to be more advocacy available to NDIS participants.

"Look I can still do it, I'm 59, if you screw with me I'm your problem ... but I'm ex-public service. So I'm happy to advocate but some parents aren't," Ms O'Dea said.

Brain cancer survivor Sarah Mamali said she was unable to get funding through her package to pay the $40 taxi fare to her GP, who was 40 kilometres away.

"The benefit of the NDIS is that it gives you independence. To have that and lose it is a problem," Ms Mamali said.

Mark Newman, who lives a regional area outside Canberra and is a full-time carer for his wife, said he'd had trouble finding service providers who would come out to his home.

"It's taken me three years to find someone to do that," Mr Newman said.

Mr Newman also said he'd also encountered a staggering lack of empathy from a local area coordinator who did their last review.

"We spent over two hours in an unconditioned room with a LAC who didn't know us, wasn't aware of my partner's condition, didn't really have any empathy for my partner's condition," he said.

"And in the end, I had to leave cutting the interview short because she was in tears because we sit there for two hours talking about her condition, all the issues she had, all the things she can't do, which is somebody who's in that sort of state is quite confronting."

NDIA acting chief executive Vicki Rundle acknowledged the experiences of some NDIS participants had been "unacceptable".

"It is just so far from the experience we want people to have. It does go to the training and the the supervision of our planners and remembering that our planners do the best they can."

However she blamed the rapid growth of the scheme for the failures.

"We've had a rapidly growing workforce, and I'd ask people to think about any other rapidly growing workforce anywhere," Ms Rundle said.

"You know that we were also given recently more [room under the Average Staffing Level cap] and at the moment we believe we're still recruiting and so our experiences that we will have sufficient numbers to be able to do the sort of things we need to do, but we also need to train them and get them working consistently. But I would like to put a plug in for our planners, I realised that that it's not always perfect, but they none of them mean any malintent."