Insurance cancelled, debit order still processed

Despite sending Discovery Insurance an e-mail in good time to cancel my short term, they still put through a debit order in excess of R 2600.00. My initial mail complaining about this was sent +/- 27th May 2015, and their initial reference *** refers. 6 e-mails have since been sent - still nothing has been resolved. The last 2 e-mails even had the Short Term Insurance Ombudsman in copy. To date, I am still waiting for my refund.