Random amount added to loan after loan paid up

Please will someone assist

My wife was sent a statement last month advising that her loan will be paid up after the last amount of R439

She then this month received another statement out of the blue with another R586 added to the loan

We tried speaking to the consultants over the phone but they were absolutely awful to try and explain the situation and just kept telling us to pay it.

The lack of customer support is remarkable

Please get this sorted ASAP