More than 20,000 allegations of abuse by home care workers against elderly and vulnerable people have been made in the last three years, figures show.
Data obtained by the BBC under the Freedom of Information Act revealed the claims included 12,000 allegations concerning neglect, 2,400 cases of psychological abuse, more than 3,400 allegations of physical abuse, as well as 400 claims of sexual abuse.
The vast majority related to care of elderly people in their homes, with more than 9,700 involving people aged over 80.
The BBC File On 4 investigation also sought to find out what action was taken following the allegations.
The FOI data showed prosecutions are rare, with just 700 of the 23,428 alerts resulting in police action and 15 prosecutions.
File On 4 said it was not possible to find out whether all these reports were valid and fully investigated.
Bridget Warr, chief executive of the UK Home Care Association, which represents care companies in the UK, described the findings as "horrifying" and blamed cuts to local Government budgets.
Local Government Ombudsman Michael King said there was a growing problem over standards of home care.
Ombudsman complaints about home care rose by 25% last year to 372 and 65% of them were upheld.
The Department of Health told the programme it has "introduced tougher inspections of care services, given councils access to up to £7.6bn of dedicated funding for social care and will continue to challenge local authorities that do not fulfil their duties under the Care Act".
File On 4 detailed how some elderly people were left for days without proper medication or attention to personal hygiene.
The BBC asked every council in England, Scotland and Wales with responsibility for social care, for the numbers of allegations of abuse and neglect made against home carers who were contracted by local authorities to provide home care.
In Northern Ireland, the BBC sent FOIs to health and social care trusts.
Only half the councils contacted in England, Scotland, Wales and NI provided data, suggesting the true number of allegations could be far higher.
File On 4 is on Radio 4 on Tuesday at 8pm.