But GP care was not found to be at fault.
The report into the NHS and social services in England showed that, while there were failing by hospitals and council-provided care services, no complaints against GPs had been upheld.
It has called for an urgent review of health and social care for people with learning disabilities.
The Health Service Ombudsman and the Local Government Ombudsman published the report after investigating the deaths of six people.
The cases of Mark Cannon, Warren Cox, Edward Hughes, Emma Kemp, Martin Ryan and Tom Wakefield had been highlighted by charity Mencap.
The ombudsmen found that one person had died as a consequence of public service failure and another death could have been avoided had care been better.
The bodies have made three recommendations.
As well as an urgent review of all NHS and social care in England, they said regulators should ensure their frameworks are effective.
They called on the Care Quality Commission, Monitor and the Equality and Human Rights Commission should report to their respective boards within a year.
It also said the DoH should promote and support implementation of the recommendations made by the report.
Ann Abraham, health service ombudsman for England said the report highlighted ‘distressing failures’.
‘The recurrence of complaints across different agencies leads us to believe that the quality of care in the NHS and social services for people with learning disabilities is at best patchy and at worst an indictment on our society,’ she said.
- What is your experience of care for people with learning disabilities?
Comment below and tell us what you think