Centrelink endured an "annus horribilis" in 2015, according to a leading welfare advocacy group, with complaints surging to record levels and website meltdowns causing misery among its millions of clients.
The Welfare Rights Network says complaints about Centrelink are up 35 per cent in just two years, with more than 62,000 grievances reported through the government's official channels in the past financial year.
The office of government complaints bureau, the Commonwealth Ombudsman, confirmed this week that it was fielding complaints about Centrelink, in the five months to November, at an average rate of 660 a month.
The department was savaged in a midyear National Audit Office report for its customer service performance and ended the year plagued by serious website malfunctions.
In November and December, clients suffered through weeks of disruption to the Centrelink websites used by millions of Australians to manage their payments and report their work activities.
The agency was forced to apologise after weeks of "intermittent issues" left many clients unable to log onto their accounts.
The federal opposition says it is losing faith in the ability of the giant Department of Human Services to run Centrelink but Minister for Human Services Stuart Robert defended his department's performance, saying it had a difficult job to do.
Aaron Neal, director of Sydney's Welfare Rights Centre, said the surge in complaints and criticism from oversight agencies had made 2015 a bad year for Centrelink.
"This has been Centrelink's annus horribilis," Mr Neal said
"Despite getting the green light for a $1 billion computer overhaul it just has not been a good year for the nation's premier service delivery agency.
"In the last two financial years there has been a 35 per cent increase in the number of complaints about Centrelink.
"Centrelink is the most complained about government department in Australia according to ... the Commonwealth Ombudsman, recording a massive 26 per cent increase in complaints last financial year.
"In 2014-2015 Centrelink received 62,691 complaints about its services.
"A quarter of these were about waiting times, engaged signals and call disconnections."
Labor's human services spokesman Doug Cameron, an outspoken critic throughout 2015, agreed that it had been a dismal 12 months for Centrelink and said he and his colleagues had lost faith in DHS's ability to deliver on its responsibilities.
"It certainly hasn't been a year they can be proud of," Senator Cameron said.
"There is a growing concern among MPs and senators around the country that the department is not delivering.
"You can see it in their own annual report that customer satisfaction is at historically low levels."
Mr Robert acknowledged the recent tech troubles had frustrated Centrelink clients but said the agency had a difficult job to do and was performing it well.
"I am aware of complaints about the department's online services and I understand the frustration experienced by people when technology doesn't operate smoothly, especially when it happens during the end-of-year rush," the minister said.
"While not dismissing any individual's concerns, they must be viewed in context.
"The department does an extremely difficult job very well, reliably delivering over $165 billion in payments each year.
"It touches the lives of most Australians and handles more than 600,000 customer interactions per day, half of those through digital channels."