Seized salary because of outstanding payment?

My legal situation has gone through some real challenges. in July, I received a letter from Y. saying that I had an outstanding payment from my dentist and I would go to court for not paying it. I was not aware that I had an outstanding bill to pay from the dentist and then this letter from Y. only gave me 2 weeks to settle the payment and there was no place to appeal directly. I was not made aware as I was in South Africa for a while tending to my ill father and the death of my grandparents. I called for free legal advice and because of my salary, I wouldn't get free legal advice but they did suggest to send an appeal letter to the court, so I did. At this same time, Y. said I need to, what as I understood as, a payment to let the account move forward. I waited and did not hear if my appeal letter was considered and I got a letter on Friday the 22nd of September that due to my monthly payments not being successful, Y. is seizing a signification amount of my salary. I called them and tried to contest, saying I was unaware that I would have to set up an incasso, assuming my one off payment was enough until there is an appeal achieved from the courts. I honestly can't afford this and I am panicking and not sure how to reduce these amounts. It was incredible aggressive and has caused me to have severe mental anxiety. I was wondering if there is a way to get advice on how to appeal this / not seize my salary.