A man with Alzheimer's died after falling from his bed when a carer failed to turn up, an inquiry found.
Robert Adamson, who was in his 80s, had been unable to look after himself and was receiving night care at home from Chester-based agency Jane Lewis.
Mr Adamson was left without a carer due to "poor communication", the inquiry found. His son Duncan said the death had "taken a huge toll on the family".
The agency apologised and said it "sincerely regretted" the error.
Grandfather-of-four Mr Adamson, who was unable to get out of bed without assistance, had been receiving essential night care at his home for several months.
The night carer's role was to keep him safe and comfortable, and provide respite for his family, an investigation by the Parliamentary and Health Service Ombudsman said.
On the night of the fall, the carer did not arrive at the usual time.
When the family rang the agency, they were assured a carer would come that evening.
However, the following morning his daughter Rachel found her father dead on the floor beside his bed.
The investigation found "the agency's poor communication and administrative errors left Robert without a carer on the night he died".
"I don't know if my sister will ever recover from finding him like that," said Duncan Adamson. "It's take a huge toll on our family."
Rachel Adamson said: "Night care enabled my father to continue to live safely at home with my mother.
"His death in the absence of a carer demonstrates how essential that support was.
"Our family's loss has helped ensure that the same thing does not happen again and others do not experience the distress that we did."
'Cannot happen again'
Becky Garnett-Buchma, managing director of the Jane Lewis agency, said it had "profoundly apologised" to Mr Adamson's family for the "service failings on the night of 8th August, 2016".
She said it was "an isolated incident" and that the agency has "learnt from it, fully implementing the recommendations of the ombudsman to ensure such an incident cannot happen again".
Rob Behrens, parliamentary and health service ombudsman, said: "While we recognise health care staff are under significant pressure and applaud the fantastic job they do, communication and reliability are key elements of their work and, when things go wrong, it is vital that this is recognised and steps are made to improve services."