Ontario ombudsman André Marin released his annual report on Tuesday. (CBC)

Ontario's ombudsman says an agency that helps single parents get court-ordered support payments is giving up on difficult cases.

In his annual report, André Marin says the Family Responsibility Agency had been closing cases it found "impractical to enforce" and clearing accounts owing once a case was deemed closed.

He called the agency one of the "most consistently complained-about organizations."

Marin says a woman whose husband owed her $165,000 in unpaid spousal support over 10 years was turned down by the agency, forcing her to collect more than $11,000 in social insurance.

The agency has been criticized severely in previous ombudsman's reports as suffering from what Marin called "customer disservice syndrome for failing to reduce the amount of child support arrears in Ontario — which was up to nearly $1.5 billion in December."

A single mother of three who was forced to go on welfare due to lack of payments found out the FRO had mistakenly wiped out a debt of more than $60,000 in child and spousal support owed by her ex-husband — and was told she was only owed $5,400.

Those findings were part of the ombudsman's fourth annual report, which looks back on his office's latest investigations and the more than 16,000 complaints reviewed last year.

His key concern last year was an inability to investigate complaints about municipalities, universities, schools, hospitals or children's aid societies — an issue that came up again in this report.

Earlier this month, Marin launched a probe into limited funding of a chemotherapy drug regardless of patient response to the treatment.

In March, he complained about how parents of special needs children were still being asked to give up custody to get their kids treatment, despite government promises to stop the practice.