Disabled and sick Australians were waiting for more than half an hour, on average, just to talk to Centrelink on the telephone at the start of 2017, the agency's latest figures show.
The average wait time on the Disability, Sickness and Carers line has ballooned out from 21 minutes and 18 seconds in July 2016 to more than 31 minutes in January 2017.
The new data, released by the department to the Parliament, show the average waiting time across Centrelink's "main business" phone lines was nearly 27 minutes in January.
The same month, at the height of the robo-debt crisis, Human Services Minister Alan Tudge claimed the average waiting time for phone calls to Centrelink was 12 minutes.
Opposition Human Services spokeswoman Linda Burney said the numbers showed the government was in denial about Centrelink waiting times.
Mr Tudge's office was contacted for comment on Tuesday but did not respond before deadline.
The real waiting times can be much longer than the average, as DHS regards a call as answered if the caller is put back on hold and spends further prolonged periods waiting to speak to a person.
Centrelink has been subject to sustained criticism for its customer service efforts for several years, coming to a head in late 2015 when the National Audit Office found Australians had spent 143 years on hold to the welfare agency in the 2013-2014 financial year.
The latest serious deterioration in customer service standards is consistent across all Centrelink's phone lines in the six months from August 2016 and January 2017.
The average wait on the Families and Parents line went from from eight-and-a-half minutes to more than 24 minutes, Participation Solutions callers were waiting more than 35 minutes on average in January to talk to a person and Employment Services callers faced an average wait time of more than 33 minutes.
Ms Burney said the government was acting tough on "welfare cheats" while putting honest Centrelink clients through a nightmare.
"The minister talks tough on alleged welfare cheats but the reality is for people who want to do the right thing just reporting their income or clarifying their responsibilities can be a nightmare," the Labor frontbencher said.
"This data only counts the time it takes for Centrelink to answer the phone, even after that happens clients are often put back on hold or transferred between staff for much longer and, in some cases they can't even get through.
"This isn't even the full story."
Ms Burney accused the government of "pretending" that people stood a realistic chance of getting through to centrelink.
"Whether it's the robo-debt disaster, claims processing time blow outs or phone wait time, all we get is spin from this government," Ms Burney said.
"The government has already flagged that the upcoming budget will be attacking students, they've already started by making their lives more difficult when they want to contact Centrelink."