African Bank refuse to restructure my monthly installment & i explain to them i cant afford it anymore?

I have a loan with African Bank and i phoned them to request that i cant afford to pay the extra installment im paying, can we take it back to the initial agreement. I was paying R6700.00 then requested that i pay extra so i can finish my loan quicker but due to Financial constraints lately its difficult. Now African Bank refused they say they can only minimize my installment for 3 x months then get back the outstanding money and pay the high installment again. Now i am really confused as i know my financial situation but they are forcing me to skip the payment so they can black list me??? Hello Peter please help me to explain to African Bank i cant afford R8900.00 installment lets restructure my payment to the initial agreement of R6700.00.