Non closure of account

I had a personal loan with them which was debitingR2400. On the last months installment they debited R2238 and told me i have a balance of R172. If i ask then why they did not take the whole R2400 which was gonna cover the whole amount, there is no answer. Then i asked to pay the balance of R 172 in order for then to close the account, to my suprise they said i must pay R 533 to settle R172 which does not make sense at all. Today i paid them that R533 and called them to close the account only to be told the money is not reflecting and they cant close the account. I requested atleast an email where i can send proof of payment the lady refused and said i must call tomorrow again. To me its like i will owe them for life now, because next thing i will be told to pay interest for this R172 of which i still dont understand what made it to be settled by so much. They saying u owe us R172 but u must pay us three times for us to close this account.