Ombudsman Act 1975, s 13
The Ombudsman investigate complaints from members of the public about the decisions or conduct of government bodies and officials and other public bodies like the Accident Compensation Corporation.
The Ombudsman can’t usually investigate ACC‘s decisions about claims, such as whether to accept a claim, or whether to provide treatment or pay compensation. In these situations, you can have an independent review and, if necessary, appeal to the District Court.
However, the Ombudsman can investigate other types of decisions and actions by ACC, such as:
delays in responding to your letters
actions taken by ACC in getting you to repay a debt to them.
(For how to complain to the Ombudsman, see “Challenging decisions and conduct of government agencies” in the chapter “Dealing with government agencies”.)