Sonya Ludlow is a strong woman. When you're bringing up seven children, resilience and thick skin are almost compulsory.

But the Adelaide mother was left feeling "absolutely awful" after a review of her eight-year-old son Samuel's funding National Disability Insurance Scheme (NDIS) plan.

"[The NDIS representative] more or less said, 'by my sixth child I should know how to be a parent and how to look after my children'," Mrs Ludlow said.

All but one of her children sit on the autism spectrum.

The nine-month review was sparked after Sam's funding package was thousands of dollars less than expected.

The Ludlows maintained fortnightly speech therapy and occupational therapy sessions, assured the review would be wrapped up quickly.

But by December last year, Sam's funding cut out, and, unable to afford $150 sessions, the family was forced to withdraw him from the treatment. He only returned last week.

"I've got lovely support through my beautiful husband [David], but I often wonder if I was a single mum whether I'd be able to do this."

Sam Ludlow playing at a playground in Adelaide's northern suburbs. ( ABC News: Haidarr Jones )

Last December, Sam's case was one of about 14,000 sitting in the NDIS's review backlog, according to a damning ombudsman's report this week. Then, about 140,000 participants were in the scheme.

The review queue has since shrunk, but the agency in charge of the world-first scheme — a Commonwealth department known as the National Disability Insurance Agency (NDIA) — still receives about 640 review requests each week.

Some of those requests do not reflect badly on the NDIA. People can request an unscheduled review if their circumstances change, for example if their condition improves.

But the agency often is culpable when it comes to another type of review, known as an internal review. People ask for these when they disagree with the plan and funding package they are given.

Some reviews come from people who feel short-changed, given the state government support they previously received, or because of the high expectations associated with the scheme.

But the Government is also to blame. The NDIS's full-scheme launch in mid-2016 was a disaster. The computer system failed. A backlog of NDIS applications quickly emerged.

Plans were then often completed over the phone and rushed. Key staff lacked training and experience. There was little consistency in the decisions being made.

Social Services Minister Dan Tehan. ( YouTube )

The scheme's IT system remains hopeless, and elements of its bureaucracy are not much better, according to the watchdog's report.

The agency accepted all 20 of the ombudsman's recommendations, and Social Services Minister Dan Tehan said work was underway to bust the backlog "over coming months".

"It's something that we need to address, and it's something we are addressing," Mr Tehan said.

"Special teams have been put in place to address this issue."

'There are enough challenges in life for us as a family'

Damian Palmer with his daughter Bethany Palmer at home in Sydney's northern suburbs. ( ABC News: Dan Guia )

Damian Palmer secured an NDIS plan in November 2016 for his daughter Bethany, now 18, who has a profound intellectual disability.

Since then, he said dealing with the agency had been a source of "constant frustration".

"It just gets debilitating, it just wears you out," Dr Palmer said.

"There are enough challenges in life for us as a family."

After receiving his daughter's first plan, the Sydney-based academic quickly demanded a review.

"She is tube-fed, but there was no funding for the required equipment," he said.

Dr Palmer said the NDIA did not clarify what type of review he wanted — an unscheduled review or an internal review — and then wrongly conducted an unscheduled review.

"And that meant if we weren't happy with the outcome … we weren't able to go to the Administrative Appeals Tribunal," Dr Palmer said.

"In [the unscheduled review] they decided to take away $20,000 funding they'd originally allocated for an assistance dog."

Dr Palmer and his wife Christine secured additional funding for the tube-feeding equipment and other supports, but then had to run an online fundraising drive to secure the assistance dog.

'Staggeringly bad' internal processes

Some of the NDIA's processes are staggeringly bad, as highlighted by ombudsman Michael Manthorpe.

He had to explicitly recommend the agency, "clarify with the participant whether they are seeking an internal review of [a] decision or a reassessment of their plan".

The computer system used by the NDIA automatically spat out the wrong letter after an internal review decision has been made, Mr Manthorpe noted.

"The participant may end up with only one [incorrect] letter or two [conflicting] letters."

The ombudsman also pointed out the agency's computer system and processes did not allow staff to make simple changes without triggering a full plan review.

The NDIA said it was currently updating its IT system, and trialling face-to-face planning sessions.

Key questions are: how quickly will the computer systems be fixed, and the planning process be improved?

Both need to happen soon — almost half a million people will be part of the $22 billion-a-year scheme within three years.

Shadow Minister for Families and Social Services Jenny Macklin. ( Alan Porritt, file photo: AAP )

Federal Labor is demanding the Coalition lift a staffing cap imposed on the NDIA (which curiously does not limit the number of contractors that can be engaged — staff often with little disability sector or public service experience).

The Government could also accelerate investment to fix the agency's dud computer system.

Sure, this would be an upfront budgetary hit, but it would not be ongoing spending. It could cut the number of reviews needed, reduce the number of NDIA staff required over the medium-term, and help ensure the NDIS's dramas do not spill into the next decade.

Quickly remedying the NDIS's problems would also ease the burden on people with disabilities and their families — those the scheme is there to support.

As Sonya Ludlow put it: "I wish it was just easier."