I now live in fear of Centrelink, even though I am dependant on their payments to survive

I have been diagnosed with depression and an anxiety disorder. Most of the time this is manageable, but sometimes it becomes incapacitating, to the point where I have been hospitalised. Any stressful situation doesn't help my symptoms, but my recent dealings with Centrelink have sent my stress levels through the roof.
I also have an autoimmune disease which effects my ability to work and leaves me constantly fatigued. As well as this I experience chronic pain from a shoulder injury. Needless to say, stress makes these problems worse.

About my employment and dealing with Centrelink:
From July 2010 to Nov 2010, I did casual work for a company that produced educational videos. During this time I earned a total of $8910.
Once this job ended, I applied for Newstart. I received my first Newstart payment in Jan 2011.
After hearing about so many people being threatened with false debts, I naturally became frightened that this might happen to me, so in early Jan 2017 I checked my personal page on the Centrelink website.
There I found a letter pointing out discrepancies between information Centrelink had received from the Australian Tax Office and information they had received from me.
This concerned the amount of $8910 I had earned in 2010. I thought this was strange, because I had earned this income before I ever went on Newstart, so I didn't understand why Centrelink were asking me about it. I also realised that I had made a mistake: I was meant to have completed this online form before the end of Dec 2016. I don't know how I'd missed this letter, but clearly I did and I admit it was my fault.
So now, quite anxious about the repercussions of filing the form late, I quickly confirmed the details it asked. There was no other information given, no explanation of what the discrepancy was, so I simply confirmed the name of the company and the amount I'd earned. I thought these were the details Centrelink were after, so ticked the yes boxes and submitted my form.
However, I didn't realise their was another small icon I was meant to click on: a part of the form that allowed me to change the start and end dates of my employment. Because Centrelink had given no indication that the dates were the discrepancy, it didn't occur to me to check that. Once the form was completed, it disappeared. I had no way to go back and correct it, and a message was generated telling me I would receive a judgement within 14 days. I had no idea what this meant and was now frightened that I'd be hit with a false debt.
Concerned, I called Centrelink to find out what was happening. After waiting on the phone for over an hour, I spoke to a staff member named Jason. At this stage I was very anxious that I'd incurred a debt. Jason said this was likely.
It seems the problem was that the Payment summary for my work at the video company I had supplied to the ATO for the 2010/2011 financial year didn't specify the date my job ended. It simply stated how much I'd earned within that financial year. The Centrelink computer system then automatically averaged the amount of $8910 over the entire year. This made it look like I'd earned employment income while I was on Newstart, even though I hadn't. I was being accused of not declaring my income, even though that income had stopped a month before I received a Centrelink payment. I have no idea why the system automatically does this. It seems like a really stupid and inaccurate way to go about it.
I was panicking now, but Jason said if I could obtain an Employment Separation Certificate from my former employer, I might be able to get the debt cancelled. Jason offered to call the company and get the certificate for me, which he did. But this took 24 hours, and in the meantime I was distraught, not knowing how much I might have to pay or by what date I had to pay it. I was so upset I could barely eat or sleep. It got to the point where I felt suicidal and phoned Lifeline three times within 24 hours.
The next day I called Centrelink again. It took an hour an a half to get through to an operator. This time I was told there was no debt, that my file indicated I wouldn't have to pay anything. But the staff member seemed a bit vague about it, and I wanted to be absolutely sure that I wouldn't be hit with a debt within the next 14 days.
So I spent another hour+ on the phone. Again the operator said there was no debt, but told me I could call Earned Income Intervention on 1800 086 400 to make sure. I was put through to a staff member, then cut off. I called again and was put through to another staff member who then explained that I did have a debt. I was being asked to pay $2126.53 plus a possible recovery fee because I had filled a form in late and the computer had automatically averaged my income over the whole year. He said the debt couldn't just be reversed even if it was incorrect. He said I had to do a Reassessment online, and that a compliance officer would then let me know if I still had to pay it.
Now I was really upset. I checked the Money Owed section on my Centrelink page, and sure enough, there was the $2126.53 plus a demand that I arrange a payment plan before 09/02/17.
I completed the Reassessment online (note, I don't have access to the internet at home because I can't afford it, so all this must be done on the computers in the local library - where the internet often doesn't work - or at a relative's house 30 mins walk away) with a staff member from Earned Income Intervention talking me through it (she was very patient and tried to be helpful). At times the website was glitchy and wouldn't let me submit documents, which was very frustrating. I asked the staff member if the documentation was sufficient and she said it should be fine, even though it didn't have the correct employment dates on it. I then submitted the reassessment form and was told to wait up to two weeks. Fortunately I only had to wait a few hours for a result - it looked like my reassessment had been rejected, but there was no explanation why.
I was beside myself at this stage. I went to email Jason, the staff member who had helped me before, because I was too upset to speak to another Centrelink staff member or wait another one or two hours on the phone (when I had been cut off 3 times). I found that Jason had emailed me the Employment Separation Certificate.
I did the online income reassessment again, this time uploading the ESC with the correct dates to see if this would do anything. Again there seemed to be a problem with uploading documents. I had to do it several times, and then when I checked there was no indication the documents had uploaded. At this point I gave up and submitted the assessment anyway.
This morning it seems my debt has been cancelled, with no explanation. So I don't know if that's the end of it, or if another random debt will be generated against me at any time. I now live in fear of Centrelink, even though I am dependant on their payments to survive.

It took 3 days and endless hours on the phone and endless stress to sort this out. And in the end I still don't know why the debt was issued or why it was cancelled. This fake debt caused me to have a complete nervous breakdown: screaming, crying, collapsing on the ground and shaking uncontrollably. I became suicidal and had to call Lifeline three times within 24 hours. I couldn't eat or sleep. It has seriously been one of the worst experiences of my life. I am now off work for two weeks with a medical certificate and I have to take medication to get to sleep. I feel utterly traumatised by this fake debt. I live in fear of it happening again. I am still paralysed with anxiety and can barely function.