MYKA review: necklace/ not received for christmas

I purchased a necklace as a christmas present for my daughter and paid extra to have it delivered for christmas. It still has not arrived and i have been told I will have to pay 30% of the cost to return it. The ORDER NUMBER: [protected]
I have emailed but got no response. I was guaranteed delivery for christmas.
I wish to get a full refund. I have since been told it is lost in the post but still have not been offered a refund.