Debited twice and no response on refund

I made an online reservation on 8 November and my credit card was debited as payment. I then received a message that the reservation was unsuccessful. I repeated the process and the result was the same. I later received an email stating that the reservation was now successful. As I had been debited twice I requested a refund. I was subsequently requested to provide proof which I did on 13 November. I have requested updates on the progress, but get no response.