Unathourised debit order refund

Please assist me in getting my refund from an unauthorized debit order from Absa idirect. I cancelled my cover with them by sending an email on the 25th of August due to the ********** service I received when they were due to pay out my cashback bonus. I was alarmed when my account was debited and called to inquire and request for a refund. The consultant said they never received my email, it could have been sent to an incorrect address as I should have received an automated response if I had sent it to a correct address. I forwarded them the automated response which came after writing my intent to cancel the cover but nothing has been done. My account should have not been debited and my bank refuses to reverse this debit. I have sent several emails to Absa RBB My Business Banker and the last response I received from Moipone Maile stated that they cannot reverse a debit order from FNB after having been sent from pillar to post and having asked to fill in a debit order reversal form. Please assist me in getting my money back, thank you.