LIABLE FOR PAYMENT AFTER CANCELLING MEMBERSHIP

I app**** for vehicle finance online via Finance turtle in the month of August 2015. I was unsuccessful and debited on the 20th of August for membership and service fee. On the 21st of August 2015 I called to cancel the membership and was advised to send an email which I did. I then received response on the same day that the membership was cancelled. To my surprise I recently been receiving statement that I owe R1500 and legal action to be taken against me. There is a call recording for this and have sent emails demanding to know how can I be liable for a service I never used and advised that it was cancelled.