I've just quit answering the phone

I was recieving a part single parents payment as I worked part time.
On my reporting days, I would over estimate just to make sure I didn't end up with any overpayments.

Jan 2015 I finally got 2 jobs and was thrilled, to never have to listen to their instrumental elevator music on the phone, not have to be questioned or judged or worried by Centrelink ever again.

So it was either late 2015 or first part of 2016, I recieved a letter, stating I owed Centrelink in excess of $6,000.
My yearly income for around 10 years was between 23,000-28,000.
And (they write) its a debt from around 2012?? WTF how is that fair? I know I never once tried (maybe wished) for extra money.

Originally I assumed I just had to accept it, that somewhere along the line I messed up, but for a debt from 2012 — why the hell didnt they pick up the error within weeks? months? a year? Not 4 freaking years later.

I did start to pay it off, but gradually I was hearing more stories of the same and realised they sending out debts to many many people and they were as stunned as I was. Not to mention stressed, anxiety and depression as I feel.

I tried to rationalize with someone via phone, but they just rely on what they're told.

If I had ripped Centrelink off, I could accept this bill but now I've just quit answering the phone & reading ltheir letters.

If I was cashed up, I would love to fight this debt with a good lawyer but I'm not, so burying my head in the sand has seemed the next best option (I know that's a really bad solution).

I'm pretty sure my debt as gone to "Bradstone" debt collectors.