From the article:
The man in charge of Centrelink’s new system, which is sending thousands of automated letters to welfare recipients asking them for money back, says those feeling “lost in the system” should write to him directly: hank [at] humanservices.gov.au
Last week, Hack spoke to students who say they have reported their income correctly to Centrelink but are now being accused of welfare fraud.
It's the result of a brand new system that matches the income you declared to the Australian Taxation Office (ATO) with the income you declared to Centrelink. It's able to go as far back as 2010. When it detects a disparity, it automatically generates and dispatches a letter. For the Government, it's all about clawing back billions of dollars believed to have been incorrectly paid to welfare recipients.