From the article:
Top Centrelink bosses have hung up on the public, putting their office phone numbers and email addresses under wraps.
The move came after one customer of the welfare agency went public with how he bypassed Centrelink's notorious customer service system to contact high ranking public servants directly.
[...]
DHS spokesman Hank Jongen indicated that all 167 of DHS's elite senior executive public servants had now gone ex-directory.
Only 40 million of the 62 million attempts to contact Centrelink by phone in the 2014-2015 financial year were "successful", meaning the agency answered 4 million fewer calls than it managed the previous year.
The agency's aim is to move as many transactions as possible onto its websites and mobile apps, where they are much cheaper to conduct, and away from face-to-face interactions.