Pupils with special needs who live in residential facilities have fewer protections than children in care, according to a new report by Peter Clarke, the children's commissioner for Wales.
The investigation into the state of local education authority complaints procedures, whistleblowing policies and advocacy services found that many children living away from home in another authority were not made aware of the safeguards designed to protect their welfare.
Gwenda Thomas, Labour Assembly member for Neath, who is chairing a child-protection review, has pledged to address the issue. Seventeen of Wales's 22 LEAs told the commissioner they made no arrangements to ensure that children living beyond their boundaries could easily access their complaints procedure.
Only two LEAs said they made regular visits to children with special needs who were being educated outside their area, and just two said advocacy services - which support young people who want to complain - were made available.
Mr Clarke said: "It is hardly surprising that LEAs receive so few complaints from children and young people given that the systems themselves are rarely child-friendly or accessible."
The report, Children Don't Complain, said the situation has been compounded by the fact that education departments are not subject to the same statutory duties as social services under the Children Act 1989.
Keith Bowen, manager of Contact a Family Wales, which supports the parents of disabled children, said: "Disabled children are more vulnerable so it's vital to have extra support in place for any placement away from home."
The report has recommended LEAs set up a single point of contact for children who want to discuss a concern about a particular service. It has also called for authorities to review their whistleblowing policies and for advocacy services to be available to all.
A spokesperson for the Welsh Local Government Association said: "Local authorities recognise there is scope for improvement in the quality of complaints services, but they are working extremely hard to make them more accessible to children and young people."
Meanwhile, the Assembly's review on safeguarding vulnerable children, chaired by Gwenda Thomas, will look at complaints procedures, "not only in education, but across the board", she said.
The review is concerned with vulnerable children throughout Wales, not just in education. However, it is considering similar issues to those addressed by last year's Clywch report, which came up with a series of recommendations about dealing with allegations of child abuse made against teachers.
But Mrs Thomas insisted there was no duplication. "We've been very careful and the children's commissioner is represented."
Rex Phillips, senior regional official for the National Association of Schoolmasters Union of Women Teachers Cymru, gave evidence this month. A draft report is expected by the autumn.