One said they still felt shame about what happened to them, and that the Government hadn't tried to put things right.
"Bill English, you say that you don't want the cost of a public inquiry like it cost Australia," they said.
"However you and the National Government spend money on a flag change at a cost of $26 million, a display in Dubai cost $53m, a replacement ship Endeavour cost $500m, a fleet of cars cost $6m.
"I could go on. How much value do you place on a child?
"You have to address the past before you have a hope to change the future."
Another spoke of the violence he'd suffered from his first day in state care, and the shadow it had cast over the rest of his life.
"Many times violence was meted out to me, a couple of times sexual violence were attempted.
"Out of pure fear and fighting back I became a survivor, with a very hardened personality [believing] violence is normal, along with [a] feeling of hate for authority figures who sometimes stood and watched.
"I still have bad dreams about some of the abuse done to me in the boys' homes."
The cause has won support from many corners of New Zealand.
Disability Rights Commissioner Paul Gibson said it was about justice for all New Zealanders.
"We need to know our Government cares about children and people with disabilities and will do everything in its power to investigate abuse and to put things right."
Race Relations Commissioner Dame Susan Devoy said although the current Government may not have been in power when the abuse took place, it could be the Government that made sure it never happened again.
Indigenous Rights Commissioner Karen Johansen said the politicians needed to come outside Parliament and meet the survivors in person.
"A lot of decision makers have never met a survivor of state abuse: this is an opportunity for them to do so.
"This is about justice and uplifting mana."
So far about 15,000 people have signed to support the open letter and petition.
Both will presented at the Parliament forecourt at 1pm today.
