How come?

So I have a loan with african bank,which I've been paying for 8months now,the loan was 13000 and now is 11000 which means I payed 2000 for 8months?I'm paying this loan 770 each month,now it's March I payed but the statement says there was a reversal which I don't know about,my I'd is *** please can someone look into my matter and get back to me.