Heartless terrible service

I am not happy with the treatment that i am receiving from MFC/NEDBANK. I made an arrangement to pay extra R2000 into my account to reduce the arrears, the request was accepted and approved. Since the arrangement was done, i have kept that promise until today. Now the strange part, they have increased my monthly arrangement amount to R2200 without talking to me. i have sent them email to question that but until today they have not responded to me. None bothered to clarify to me, this kind of treatment is bullying and i am not happy, i am treated as like i am useless, i do not have a say. Now the interest rates went down but my instalment instead of going down, but they increased my monthly instalment. I called to seek clarity but the consultant also did not know what to explain to me why the instalment went.