Double Debit and Delivery

I purchased an item online on the 18th December 2017 and my account was debited twice. I immediately contacted the call centre and was advised to send an email which I did. I was contacted by a gentleman who requested I send a screenshot of the double debit as well as my account number and card number... which I did. I have still not received a refund.

I tracked my order and online it states that it was delivered on the 21st December 2017. I am not sure to who it was delivered but I have not received it.

I am not sure what is causing the delay on the refund and where my order has been delivered to. This is really unacceptable.