"I've been left with a feeling that my mum's last months were in a place that nobody really cared about her."
Andrea Dunlop thought sheltered housing would allow her mother, Hazel Smith, to live an independent life safely.
But the 65-year-old collapsed and died in her flat and her body lay undiscovered for up to a month.
More than 30,000 allegations of abuse and neglect of sheltered housing residents were received by UK councils between April 2014 and November 2017.
The data, which was obtained by BBC Radio 4's File on 4 programme, also found the number of reports increased by 30% over the period.
In March 2017 police were called to Mrs Smith's flat in Wokingham, Berkshire, to force open the door.
Neighbours said they had repeatedly raised concerns about her welfare but were told she had a no-knock policy and was not checked upon.
It is believed she may have lain dead for up to a month and her body was so decomposed an inquest was unable to determine her cause of death.
Wokingham Borough Council has said Mrs Smith had opted out of the weekly warden call and had made it clear she didn't want to be checked up on, but it now asks tenants who opt out to contact the warden themselves once a week.
Andrea, from Shinfield, Berkshire, is haunted by the circumstances of her mother's death at the Wokingham Council-run scheme.
"They have a duty of care, they should have checked.
"The action was nothing to do with any of the residents raising alarm bells, it came because the postman couldn't get any more mail through the mailbox."
The BBC sent Freedom of Information requests to every council or health and social care trust in the UK, seeking the numbers of safeguarding alerts they had received about residents of sheltered housing and supported living schemes.
Just under half supplied data, which revealed that during the period covered, a total of 30,785 safeguarding alerts were received, of which the majority were in England.
The biggest reported safeguarding category in the FOI figures was neglect, which accounted for more than 7,200 cases, followed by physical abuse with 6,200 alerts, while there were 4,200 reports of financial abuse.
Government 'take note'
Prof Michael Preston-Shoot, of the University of Bedfordshire, said: "There is a lot of abuse and neglect that is happening behind an individual's front door about which the agencies are unsighted."
Across Great Britain, more than 700,000 people live in sheltered housing, which provides independent living with additional safety checks, like warden services for the elderly, as well as tailored support for younger people with physical or learning difficulties.
Prof Preston-Shoot, who chairs two adult boards in London, said action was needed to understand the scale of the problem.
"I hope government departments take a note in terms of whether they can do more to ensure we obtain an accurate indication of the prevalence of different types of abuse and neglect," he added.
A Department for Communities and Local Government statement said: "Abuse and neglect is unacceptable and must be prevented.
"We changed the law so local authorities must ensure that the services they commission are safe, effective and of high quality."
The Department of Health told File on 4 there were no plans to extend the remit of the Care Quality Commission to cover sheltered housing.
File on 4: Neglect - Sheltered from Harm is on BBC Radio 4, 23 January at 20:00 GMT - catch up on BBC iPlayer Radio.
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