My loan contract indicates that I shall pay R7 489

My loan contract indicates that I shall pay R7 489.49. I have never lapsed and yet the dashboard in my app says my next fee due for the end of April is R7 780.80 and the statement indicates interest I'm unable to make sense of. I'm seriously concerned over this R291,31 excess amount to what was contractually agreed. It affects my budget negatively and raised concerns over what causes it and if it will ever repeat going forward. I notice as well that last month I was debited R22.55 lesser than I should have. If this months excess debit is due to last month's short debit, I am disappointed because it is 100% not my doing or fault even. I do not appreciate these fluctuations. I kindly request an explanation and correction. Thank you.