Debit order taken after account has been settled

i Had three accounts with African Bank that was in arrears. i Made an arrangement to pay the amount of R450 per month as it was all that i could afford. They accepted it and we continued with the monthly payments with no problems. Then in February 2015 i received some money from a family member and decided to use that money to Settle some Accounts. I settled one loan with African Bank, And also Settled my Credit card with them. So now i have 1 loan left with them and they can debit the R450 on that one. The Problem i am sitting with is that they deducted the full installment on the African Bank Credit Card after it has been settled in full. And they took the debit order for the existing loan. Instead of going to my bank and ask them to return the money, i Rather phoned African bank to ask them why it was deducted and if they can refund it to me. They told me that they didn't cancel the debit order. So they cancelled it. I sent through my id, bank statement as per their request for refund. Now i am told they are not paying me back, but deducting it from the other loan. I feel that is ********* as i didn't give permission to do so. I had to skip other accounts to cover theirs.