Two government departments have been criticised by the parliamentary ombudsman for being too "negative and defensive" about her findings.
More than 200 pension fund holders had complained to the ombudsman
Ann Abraham said a decision by the Department of Work and Pensions to reject her ruling on pension scheme failures was "without precedent".
She said the MoD's response to her criticism of a compensation scheme for WW2 detainees was "inappropriate".
She asked the government to be "more constructive" in its responses.
Ms Abraham used her annual report to emphasise that most departments would "usually show a welcome willingness to respond constructively to my investigations and reports, and to accept my findings".
She tackled 3,600 cases for the year ending 30 March, almost a quarter of which were related to the tax credits system.
The majority - 67% - were fully or partly upheld, although that rose to 90% in tax credit cases.
However, Ms Abraham said that if many complaints "had been handled properly in the first place" by government departments, they would not have reached her office.
Approaching her should be considered the "last resort", she stressed.
The ombudsman had criticised the Department of Work and Pensions for misleading workers about the security of final salary pension schemes.
It said "inaccurate, incomplete, unclear and inconsistent" information had been provided to people "experiencing hardship and distress" when some of these schemes collapsed.
Work and Pensions Secretary John Hutton refused to accept his department was in the wrong and ruled out the payment of compensation to policy-holders.
The Ministry of Defence had initially rejected Ms Abraham's findings of "maladministration" of a compensation scheme for British people interned in by the Japanese military during World War Two.
She said some of them suffered injustice because of the department's decisions and said its approach "fell short of the standards of public administration that citizens are entitled to expect from public bodies".
Following the publication of her findings, Veterans Minister Don Touhig had admitted those affected deserved more "tangible" help.
Ms Abraham criticised "examples of unnecessary defensiveness, a negative attitude to complaints and tardiness in remedying problems".
Although it was "legitimate" for departments to contest her recommendations, she said, it was wrong "for a body under investigation to seek to override the judgement of the independent arbiter established by Parliament to act on its behalf".