The Ombudsman's Office says it is receiving a record number of complaints about government departments and doesn't have the resources to handle all of them quickly.
Its annual report, released on Thursday, shows it received 10,636 complaints during the year to June, a 22 percent increase on the previous year.
It finished dealing with 10,250 of them but Chief Ombudsman Dame Beverley Wakem says satisfaction with the office's service dropped from 66 percent to 55 percent.
"We are still significantly under-resourced," she says in the report.
"We are struggling to meet some of our timeliness targets... we currently have approximately 300 complaints on hand that we do not have the resources to immediately progress."
The office has 70 staff and an annual budget of $8.7 million.
The government has approved a $300,000 increase for the 2012/13 financial year and will extend a $370,000 temporary allocation for another 12 months.
"Together these sums go some distance towards alleviating our immediate concern about being able to pay the bills," Dame Beverley says.
The report shows a huge spike in complaints about the Earthquake Commission since the Christchurch earthquakes - up from fewer than 50 to nearly 400.
Most of them were about delays and lack of communication.