Inspectors have found "widespread and systemic failings" in services for children with special needs in part of a county.
The partnership that runs the service in North Northamptonshire has been told it must address the issues "urgently".
The inspection team found that children were suffering because support was not being provided quickly enough.
Officials have apologised to "all those children, young people and their families who have been let down".
Services for children with Special Educational Needs and Disabilities (SEND) in North Northamptonshire are provided by a partnership of the local council and the NHS Integrated Care Board.
The new report follows the first inspection carried out by the Care Quality Commission and Ofsted.
The report says that there are "widespread and/or systemic failings leading to significant concerns about the experiences and outcomes of children and young people with SEND, which the local area partnership must address urgently".
On waiting times, it adds: "There has been a failure to address excessive waiting times for access to services, such as speech and language therapy, mental health services, and all aspects of the neurodevelopmental pathway.
"This negatively impacts on the lives of children and young people with SEND."
The report added specialist equipment sometimes took a long time to come or was not available at all.
Julie Heron, a mother of two children with autism, told the BBC: "It's a battle from the start for absolutely everything that they need."
"The report is not a surprise, anybody that's within this system sees that it's actually failing. Hopefully now, people will take notice and there will be accountability."
In a joint statement, Jason Smithers, North Northamptonshire Council's leader Jason Smithers and Toby Sanders, the chief executive of NHS Northamptonshire Integrated Care Board, said: "We fully accept and acknowledge the findings of the Ofsted report and are sorry to all those children, young people and their families who have been let down.
"It is our absolute priority to ensure immediate action to drive the urgent improvements which have been highlighted."
Sam Baker, the director of Northamptonshire Parent Carers Voice said: "Sadly, the findings of the inspection accurately reflect the reality of lived experiences that local families often share with us and the concerns that we frequently raise with services.
"Urgent and comprehensive action must now be taken by the Local Area Partnership to address the systemic failures highlighted by the outcome."
From BBC