Unauthorised deduction of Premium

I signed up for car and household insurance with Discovery Insure (effective 01 December 2015) on 2 November 2015 but cancelled on 16 November 2015 when I received an offer with a lower Premium from a competitor.<br> <br> I called Discovery on 16 November and cancelled the policy but on 2 December they deducted a Premium (not the full one) from my bank account.<br> <br> I called their call centre on Friday and was told I have to e-mail their complaints department. I e-mailed them on Friday but have yet to receive a call or an e-mail response to my complaint. <br> <br> This is terrible service and I demand a response and a refund of the Premium they deducted without authorisation!