For nearly six months, Nicole Lim says her son Carlos Blanch, who has autism and is non-verbal, came home from school every week with cuts and bruises on his arms and legs.
The first time it happened, in March this year, Ms Lim went straight to the principal to ask for better supervision for Carlos, 11, who is in year 5.
"It was completely disregarded, nothing ever happened," Ms Lim said.
She eventually went to the Department of Education, which arranged a meeting between a department officer, and Ms Lim and her husband.
"There was never any explanation for what happened to Carlos," Ms Lim said.
"They just said they would [make sure he was supervised], but again, I found that he wasn't.
"When I went to pick him up, he was lying on the concrete eating rubbish and dirt. My son was unsupervised, the teacher wasn't doing her job."
Ms Lim said Carlos hasn't been to school for the past four weeks.
A spokesman for the department said: "This matter is currently under investigation by the Department of Education."
Ms Lim's claims come as a highly critical parliamentary inquiry report, released on Thursday, found that the level and number of "allegations of ill-treatment of disabled children in New South Wales schools ... are unacceptable".
The report, on the education of students with a disability or special needs in NSW, highlighted numerous submissions outlining "blatant abuses suffered by students ... such as 'caging and isolation ... in a blackened out cupboard', facial and head injuries and unexplained bruising, 'severe and bloody injury' and 'permanent scarring to multiple body sites'".
It also heard reports of "sexual and physical assault", with parents discussing the emotional impact and trauma experienced by their children as a result of ill-treatment and exclusion.
"[A] parent gave the example of her young son who 'became clinically depressed and indeed suicidal because he was marked out as so different from his peers'," the report stated.
"She declared: 'There should be no child at age six who feels so deeply that they do not fit into a mainstream school that their option is to end their life.'"
It also found the increasing use of "restraint and seclusion" in NSW schools, and noted that evidence submitted to the parliamentary inquiry matched the findings of a damning NSW Ombudsman's report on behaviour management practices used in schools released last month.
Inquiry participants noted that "students with disabilities are often subject to practices that would not otherwise be deemed lawful or acceptable for students without disability".
The report also found issues in the way complaints were handled by school authorities, including the Department of Education.
"Criticisms were levelled at the department for fostering and perpetuating a culture of discrimination against students with disabilities and special needs," the report stated.
One participant described "the department as being defensive in nature, prioritising the protection of their staff and legal staff" and "urged for a change in culture".
Following findings that an increasing number of parents are removing their children from mainstream schooling, with some exiting the education system completely, the report recommended that "the NSW government formalise a presumption" that all children should be "educated in an inclusive mainstream setting", except in "compelling" individual circumstances.
The extensive list of recommendations also included a reform of the Department of Education's complaints policy so that principals were not investigating complaints against themselves.
Ms Lim said the school and department had not responded adequately since March, and she had contacted the police and was now talking to lawyers about taking legal action.
"I'm so unhappy with the Department of Education, shame on them," she said. "I think they're totally protecting their staff."
She said her son was "traumatised" by the experience.
"He used to be very happy to go to school but then his behaviour started to change this year," Ms Lim said.
"He wasn't smiling any more, he held my hand very tightly and put his body close to mine [when I went to drop him off]; he was very scared."
David Roy, a lecturer at the University of Newcastle, who was involved in the establishment of both the parliamentary and Ombudsman's inquiries, welcomed the findings and recommendations of the report.
However, Mr Roy said the report was "indicative of what's happening mainly in public schools" and the procedures at independent and Catholic schools also needed to be investigated more thoroughly.
Labor's education spokesman Jihad Dib said: "This is an incredibly damning report into the way the government supports students with disabilities in schools and the recommendations must be implemented."
The government is due to respond to the report's findings and recommendations in March next year.