Took more money then contract and no feedback why

On 20/12/2014 I took a loan with a repayment of R3084 on 26/01/2015. On 20/01/2015 I requested a settlement amount and Phindile quoted me R2842 which I payed. On 26/01/2015 R584 was debited from my bank account. Total repayment R3426. Made contact and Annah referred me to Collections for a refund. Charlize Smith came back to me and said the settlement amount was wrong and the debit order was correct. I asked why the repayment amount went up from R3084 to R3426 when I settled earlier then the repayment date and I still have not had any feedback. Why where there extra fees and intrest added when I settled the loan earlier then the repayment date? Surly this can not be legal?