Been battling debt for years!

I have been dealing with this debt for years, I originally apparently owed over $4500 from Single Parenting Payment, which I tried to fight but with my anxiety and depression and what not, I gave up and agreed to pay a certain amount fortnightly. I finally paid ALL of this off, just before the final payment. I got another letter saying I owed over $3000 for the period of Jul, 15 to Jun, 17. Again tried to fight but just gave up because I was waiting hours on the phone, never getting the letters I asked for. I now still owe $1871 of this debt, never once have I seen how they got this debt amount. I called numerous times for letters on how they got to these amounts, never actually received anything though. Then just to top it all off, remember I'm a single Mum, I got a part time job when my son was 2 to try and help with money as these debts were just affecting my mental state and constantly worried about everything. They took my whole family tax payment end of year balance, which is $1200.! The only money I can afford to actually take my son anywhere special.

But that's not where it stops, I then got told when my son turned 8 I would need full time employment, which I then found. My son turned 8 on June 21, my new job started June 25 full time. I was in the stages of swapping from single parent payment to newstart in this time. I received one payment of Newstart which was $337, I got my pay check and reported my income and then was told I now owe centrelink $386!?!?!?!? from over payment for the period of Jun 21 to Jun 27th, 2019.

I was told by my job provider as a job seeker, I was entitled to a one off payment of $300 for work clothes and what not for getting the job, Centrelink said NO because I was between payments. I have requested documents on how they came to these findings considering I hadn't even received the amount they wanted for a newstart payment, its now August and I am still waiting on the paperwork to be sent on how they came to these findings.