A man claims to have been overcharged by nearly £2,000 for his father's home care by Leicestershire County Council.
John Holmes, from Blaby, claimed that over 16 weeks he paid an extra £1,800 for hours that were not provided.
Mr Holmes said he was now dealing directly with the service provider, which is billing him for the exact number of hours of care provided.
The council said it was investigating and the package - paid for with a flat fee - could be adjusted if necessary.
Mr Holmes's father began receiving adult social care at home after leaving hospital in February.
He said the care company was providing the authority timesheets for the exact hours carers worked, while he was paying the county council a flat fee for a weekly package.
"We didn't know whether my father would need 10 or 30 hours because it was a new experience for us," he said.
"We are being charged for 31 and a half hours a week and the maximum my father has required is about 26 in his first week at home, now it's around 22 hours.
"Initially I felt exceedingly cross, after a while words fail me.
"We've ended up dealing with the carers direct because they will invoice us for the correct number of hours."
Mr Holmes added the payment system should be more flexible.
In a statement, the authority said: "We always want to make sure that the care arranged for people is at the right level to meet their needs.
"If more care is organised than required, we would ask the individual or their family to contact us so we can review the situation.
"If less care is needed in the longer term, we can amend the support package and reduce the charge accordingly."