Failed Debit orders

I was contacted by Shantal Pillay on the 29th August, advising me that my Damelin account is in arrears and payment is required. To my knowledge, the debit instruction runs on my pay day, which will always ensure sufficient funds for my debit which amounts to R788. I contacted my bank (FNB) on the 30th August and queried the debit, the consultant advised me that (1) the debit order has not been stopped by me or FNB, (2) the last debit order instruction for this bill was the 25th May, no further debit instructions were sent and that I would need to take it up with Damelin. I gave this same information to Shantal on the 30th August as per the attachments, to which no response was received. I followed up on this matter on the 19th September to which Shantal responded that my debit has since been rejected and their debit order department confirmed that the debit was stopped at the bank. Shantal then asked me to forward my bank statement to her so that they could resolve it with the bank. I advised that my bank statement wont show any debits for damelin and I sent her a list of my stopped debit orders since 2016, of which, there is none for Damelin. Shantal is now advising that I should contact their DCC accounts manager because they CANT QUERY with my bank, but all the proof of what she said is in the attached emails. I need this matter resolved, because I am now being pushed from pillar to post for a debit I did not stop.