Mother-of-two Suzie Robertson says she feels blackmailed and pressured by the National Disability Insurance Scheme review process.

Her son's claim has been under review for 15 months and she said the experience had caused "momentous stress".

"The wheels began to fall off" when she was told she would only receive funding for one of her son's disabilities.

Ms Robertson said her son was worse off under the NDIS because he was unable access services he had previously been able to.

The NSW resident said she felt bullied by the process.

"When we were speaking to the planner he was using language like 'You want a Mercedes Benz plan but your child is only eligible for a Mini Minor plan'," she said.

"I was really shocked that was said to us.

"It made us feel awful, that we were asking for something my son didn't deserve, that we were asking for more. Everything we were asking for was exactly what he had prior to the NDIS."

Ms Robertson said at one point in the review she was offered funding for extra support, only to be told her plan would be cut into a quarter if she agreed to it.

In a statement, the National Disability Insurance Agency acknowledged Ms Robertson's experience and empathised with the delays.

It said the agency was looking to progress her son's review and achieve a satisfactory outcome.

NDIS more challenging in regional areas

Ms Robertson said while the concept of the NDIS was great, in regional areas it did not translate as well.

"In regional, remote and rural areas you don't have the providers there," she said.

Jenni Fenton, with her daughter Maala, says dealing with government paperwork is time-consuming. ( Supplied: Jenni Fenton )

"We were funded for a therapy assistant, but there are no therapy assistants on the NSW mid-north coast."

He son is unable to access an occupational therapist because the wait times have become significant in the region due to an influx of people accessing funding.

In northern NSW, Bellingen mum Jenni Fenton is about to go through the review process.

Her daughter Mala, who has celebral palsy, is also significantly worse off under the NDIS.

"Ironically when you are living this life, the time to do appeals is very limited … you can get fully taken up with budgets, managing government processes," she said

"What we all want for our kids is ordinary lives, jobs, homes … and to do that the Government has to back that up with funding so we don't have an underclass of people."

Rollout pushed too quickly in NSW, advocate says

Disability Advocacy NSW is contracted to help people with the review process, and said the Government must do more.

Chief executive Mark Grearson is particularly concerned about the plight of regional people.

"They are a long way from anyone else so there is less access to services," he said.

Mr Grearson said the rollout had been worse in NSW, which was the first state to sign up.

"NSW has been in a big rush to get out of disability services and in doing so they have pushed the rollout too quickly," he said.

"I think that is now starting to have an effect. Other states have done it in a more gradual process."

Social Services Minister Dan Tehan said a reform of this scale meant there were issues that needed to be worked through.

He said significant work to improve the NDIS review process had already started, and the Turnbull Government had provided funding in this year's budget for the development of new service delivery models in rural and remote communities.

Earlier this week a report described the review process as "lacking fairness and transparency", and found people were waiting up to nine months for their cases to be resolved.