MISLEADING PAYMENT INFOR

I 've lodge complaining regarding my account an settlement amount that they ask me to pay an i even hv sms with the amount need to pay an i paid the amount only for them to tell me i still owe them .. Last months I was owing R637 November they told me I owe R714 Now it's December after I've paid R715 they told me.my account is still owing R136 ..

Now I want to understand how did the interest escalated after we made arrangements of paying R714.56