Cancelled debit orders

I have been sent from pillar to post and have now been sent back to FNB. I have or rather had a debit order for Damelin amounting to R788 on the 25th of every month. According to Damelin, this debit has since been cancelled by myself or my bank as the issue is not on their side. I have submitted a list of my stopped debit orders, of which the one for Damelin is not on there. Can you please investigate how this payment was stopped? As this has now placed me in arrears on my damelin account since May 2017. ref : Pm8@dccjhb 01a8c07a170525 for student # 430584 for amount R788 for my HR course was the 25th May.