The Government has promised to improve mental health but the number of prisoners attending drug and alcohol programmes has plummeted by 75 percent in five years.
And Newshub can reveal one of the chief complaints prisoners make is about health services.
The Waikeria Prison riot in January was the most extreme example of prisoner complaints. On Thursday, Corrections revealed they're paying out $1.3 million to prisoners for their property destroyed in the riots.
"We should repay people - it's the right thing to do," Corrections Minister Kelvin Davis said on Thursday.
In March, Davis ordered his department to improve their archaic paper-based complaints system after a woman was pepper-sprayed in her cell.
"Prisoners can have more confidence that their complaints will go directly to the people who'll investigate them," Davis told Newshub.
Figures obtained by Newshub show complaints from prisoners are increasing, to almost 10,000 in the last financial year - and 1170 of those were about health services.
Of other complaints, 331 were about food, 549 were about welfare, 1674 were about property and more than 1000 were about staff conduct.
"This data only gives us a very rough estimation of what the situation is like in New Zealand's prisons," People Against Prisons Aotearoa representative Emilie Rākete told Newshub.
"And even from this very bleary look, we can see that the conditions are terrible in New Zealand's prisons and they're not getting better."
And despite health being one of prison's biggest issues, the number of prisoners in drug and alcohol programmes is plummeting. Five years ago, about 6300 programmes were started, but in the last year that fell to just 928.
"None of the fundamental problems are being addressed," says Rākete.
Flanked by the Department of Corrections' top brass, Davis was grilled by a parliamentary committee on Thursday about that drop. They said it could be explained by ineffective programmes being axed.
"We know that the more intensive treatment programmes that we can adopt are going to have much greater impact," said Corrections chief executive Jeremy Lightfoot.
National MP Simeon Brown says the explanation given was "completely unbelievable".
"Kelvin Davis is essentially letting people out of jail without having them actually rehabilitated in the first place," he said, going on to describe it as "unacceptable" and that "New Zealanders deserve better".
The Government is under fire for its failure to properly address the mental health crisis - a crisis disproportionately present in prisons.
The plummeting number of prisoners getting help for drugs and alcohol should be a real concern for Corrections - when you axe bad courses, you should make sure you replace them with better ones.