No Response

I place a order on 13/11 for a dress for a wedding. They told me delivery time from Black Velvet is up to 21 working days, which was fine. When I follow-up in December they told me that the package is with customs and is not yet released. On 11 January 2018, I follow-up again and since then I got no response. I try to get hold per telephone as well as e-mail, nothing, even their mailbox on there telephone dont accept any messages. I would like a full refund, but dont know how to get response out of the company. Please help?