Rose Pizzini describes herself as a "broken person".

But it is not just the multiple spine and rib fractures that have left her broken.

It is the emotional and psychological pain she now deals with in her latest battle.

The former fruit picker and cleaner, who was injured at work in July 2016, is locked in a fight with Sunsuper, one of Australia's largest superannuation funds.

She has accused them of failing to properly pay out her permanent disability claim, and compensation lawyers say she is one of many being put under severe financial stress by the organisation.

"I cry a lot. I go to bed at night and cry myself to sleep," Ms Pizzini said.

When her savings ran dry in 2017 she said she applied for a Total Permanent Disability (TPD) lump sum but was unaware the company had recently changed its policy to make payments in instalments.

"Every 12 months I have to undergo more tests to prove that I do indeed have this existing condition," she said.

"I think it's absolutely disgusting and inhumane and a total injustice that a person who has a permanent injury is treated this way.

"They are totally aware that I'm not going to get better, that my future prognosis is poor and I will eventually need surgical intervention."

Ms Pizzini said she was now under financial stress with a dependent son, but isn't eligible for government assistance because she has a de facto partner.

"It has broken me as a person — mentally, emotionally and psychologically."

Rose Pizzini has accused Sunsuper of failing to properly pay out her permanent disability claim. ( ABC News )

Law firm Maurice Blackburn has alleged Sunsuper is in breach of the Superannuation Industry Supervision Act 1993 by paying claims in instalments rather than as lump sums.

In a statement, Sunsuper said it was confident its policy complied with all relevant laws and it consulted extensively with regulatory bodies before introducing the policy in July 2016.

Compensation lawyer Peter Koutsoukis said many members nationwide would not be aware of the changes.

"Instalments go for six years, so a person only gets a sixth of what they would normally get in a lump sum," he said.

"Each year they have to reapply to prove that they are still disabled.

"They are trapped in this system of having to get medicals and prove over and over that they are disabled and these are people who have already proved that they are totally and permanently disabled."

Mr Koutsoukis said Sunsuper was the only superannuation fund in Australia to pay TPD claims in instalments.

"So in fact, they are pioneering the downgrading of people's rights," he said.

"I think financially they think that it will be more profitable to pay people over time because money devalues over time (and) some people will die."

In its statement, Sunsuper said the policy focused on early intervention, occupational rehabilitation and where possible, helping members return to work.

"TPD Assist was developed after 18 months of research and consultation with more than 1 thousand Sunsuper members who had previously been through the claims process," the organisation said.

"Sunsuper's only motivation is to pay legitimate claims as quickly as possible and it is our recommendation that members only engage with plaintiff law firms if they really need to.

"This can avoid delays in the claims process and often hefty legal fees."

Sunsuper member Brett Maynard was diagnosed with multiple sclerosis in 2014 and is suing Sunsuper to receive a lump sum benefit. ( ABC News: Ellie Sibson )

Former truck driver Brett Maynard was diagnosed with multiple sclerosis (MS) in 2014 before the instalment policy was brought in.

He claimed to be eligible for a lump sum payment of $250,000 and is suing Sunsuper.

Mr Maynard said he has been rejected by the company on the grounds he could work.

"I have MS, it's not something I can fake … the MRIs prove everything," he said.

"Yes, looking at me you might not think I have a problem until you realise that I can't actually pick up that pen and write properly, I can't actually do up a button that's come loose without five minutes of struggling.

"Whenever I apply [for jobs] I do tell them I have MS, because at the end of the day, they are going to find out so there's no point in lying about it."

Mr Maynard said he now relied on a disability pension and his wife had become his carer.

"People need to know that what they are paying for is not necessarily what they are getting," he said.

"When the money is no longer coming in and all of a sudden you're asking for help, all of a sudden what seemed to be a friendly face has turned into a brick wall with a locked door.

"If this continues there's always that chance of bankruptcy."

Sunsuper denies 'improperly' paying its members

In its statement, Sunsuper said Mr Maynard's claim was declined on the basis that he was not totally and permanently disabled when he ceased work and it could not comment further because the matter was before the courts.

It said its only motivation with insurance was to act in the best interest of all its members.

The organisation said in a separate statement that it refutes claims it is improperly paying its members, and also Mr Koutsoukis' allegations it sought to profit from the TPD policy.

"Sunsuper receives NO financial gain by structuring benefit support payments in instalments," the statement said.

Regarding Ms Pizzini's situation, Sunsuper said it had approved the claim in December 2017.

"However, unfortunately, Maurice Blackburn withheld payment instructions until last week and, to date, has also prohibited us from talking to Ms Pizzini about her rehabilitation options."

Sunsuper also said its TPD Assist policy was designed to help members rehabilitate and return to work.

It also denied claims it was the only fund to pay TPD claims in instalments.