Unexplained charge

I have contacted African Bank with no resolve. I was offered a reduction on my installment - I was called by this number *** on the 20th of October and agreed to the installment decrease which would be effective on the next debit date of 25 October. On the 25th of October I was charged the full normal installment. No one responded to the email inquiry I sent. I checked my only statement and the inslallment amount still reflects as usual. It has not been updated. I also noticed a "Journal Sundry Charge" which I have never seen on the statement. I have had this account since 2017. It reflects as an amount in areas suddenly on my statement. I called African Bank at 11.37 after noticing. I was put on hold three times and the call dropped. What is a sundry charge? Why is it suddenly appearing at a significant amount and why does it appear in arreas? African Bank is not able to provide an answer to me directly.