Loan

So i have a loan with capitec.last payment was due on the 20th had more than enough funds in my account a debit did not go off..sent customer care an email and recieced a reply stating that account was overpaid and they will pay money back..So i do not know what idiotic employees they employ as clearly stated in email account is showing arrears.si decided to go into bramch to have this sorted a i never recieved feedback.in the branch they had the audacity to ngals want to charge me intrest on the fact that it is a late payment.i told them that according to the loan agreement that was signed debit needs to go of on the 20th and its not my fault they messed up was told its my problem..so either they rwctivy this issue or i will be taking them to credit ombudsman as this is really pathetic.