double debits

I have a loan with Capitec, per our agreement the repayment is debited from my salary account on the 20th. The debit order was processed on the 20th of Aug per usual, on the 21st of Aug the repayment was also debited from my Capitec account. Called the Call Centre, spoke to a Collections Specialist I sent her a print screen of my bank acc showing the debit order was processed. She said they havent rcvd it n i will only get my refund once the money has cleared. Im out of pocket - other colleagues who had the same problem have rcvd a refund i havent. Pls explain why n whose fault that the debit order amount has nt reflected on their side. Such an inconvenience!!!