Unfair Treatment

Last year I app**** for Unlimited 4G for any device for R479 month to month bases with Rain Data Service providers, I used it for one month if not two months then I lost my job, then I decided to called Rain to downgrade my package to pay as you use for R50. Rain did not advice me that once downgrade I must be aware that I need to adjust the way I use the data every time I use it to avoid been overcharged. After a month when I logged on in my account I discovered that I now owe them an amount of R2302.90. Then I decided to contact them requesting to make payment arrangements in terms, my request was declined. On the 04/01/2021 I contacted them again requesting for payment arrangement in terms, still I was turned down, their reason is that they don't have payment arrangements. I am willing to pay my debt, somehow they are channeling me to pay the total amount in full at once of which I am unable to pay at once due to COVID. I find this unfair because the money owe them is incurring interest, there will be a time where this amount become R3000 or R4000 how will I pay it whereas I am failing to pay the current amount in full. I want to settle this amount I owe them but I can only pay them in terms till I finish it, is possible, doable and is practiced everywhere in the country.