I'm lucky that the claimed debt amount would not be an issue to pay.
Luckily I was taught by my parents to keep all payslips and documents from a young age so I can easily prove this debt is wrong.
I don't think it is right to issue someone with a debt and threaten debt collectors if you can't correctly prove the debt.
The onus should be on the person claiming the debt and not the other way around, that is how it works in the real world.
An invoice would not be paid without substantiating evidence for works or services completed.
The amount of time it takes to submit supporting evidence is also prohibitive, I've not used centrelink for 6 years and either need to go into their office or set up Centerlink in MyGov, both options will take a disproportional amount of time and effort.