Ridiculous interest rate

I had a contract with MTN and went to check when I will be ending the 24Months contract. One of the consultant told me that I was only left with a month. I stopped paying as I was doing manual deposits. 6Months later without any point of contact I get an email that my account was handed over to lawyers (Shapiro Sheik) and that I was left with 6Months payment in order to finish the contract and that the time I was told I am done with monthly installment was when my contract was due for upgrade. I owed MTN R1800 as my installment was 299 per month and also added amount of the lawyers which amounted to R4200 I only agreed I will pay 200 a month which I did but the problem I have is that now I have to pay interests which are very much ridiculous. I am currently not working and specified that I won't be able to be consistent with payment as I am.not getting any source of income. Yesterday I was told that if I default they charge interests of about R250something.. interests that are very much higher than banks. How am I going to finish this debt with such aa ridiculous interest rate. That is very insane Please assist.