A vulnerable woman in Somerset was made to wait nearly two years to be assessed for the care she needed, a report said.
The woman, whose name has not been released, lives in supported accommodation and employs her parents to provide care via direct payments.
The Local Government and Social Care Ombudsman criticised Somerset County Council for taking too long to properly reassess her care needs.
The council has apologised to the family and will pay compensation.
It said this was to "acknowledge the time and trouble caused" by both the delayed assessment and the complaint process, the Local Democracy Reporting Service said.
The ombudsman's investigation found the council took a total of 21 months to carry out a reassessment of the woman's needs.
It also "failed to address questions" about who would pay for respite care, and "reneged" on an agreement that it would make a one-off payment for a short break.
The council also failed to backdate the woman's increased care package and failed to increase her payments to allow her father to be paid for managing her finances, the report said.
A council spokeswoman said: "We work hard to get things right every time, in this case we did not meet the standards we set for ourselves. We have considered all the recommendations and are in the process of actioning them.
"We are a learning authority and in light of the recommendations we are undertaking a review of our direct payments."