Refund Cancellation Of Hint Subscription And Written Confirmation

I purchased what I believe was a Hint premium package via their website that I accessed through Facebook, from Australia. An amount of 48.99 AUD was taken from my account, and when I noticed this, I requested a refund and cancellation of the subscription. Since then, I have repeatedly questioned this charge but have not received a proper response. When I contacted Hint, they asked me for my name and the first six and last four digits of my card details so they could process a refund. I provided this information, but they kept asking for the same details many times, approximately ten times in total, without resolving the issue, and eventually stopped replying to my messages. I am requesting a full refund of 48.99 AUD that was taken from my account and the complete cancellation of any subscription associated with my details. I also want written confirmation that my subscription has been cancelled and that no further charges will be made to my account.