No refund and lies about refund being done

These people refuse to give me my refund and are trying to convince me that the refund was done when there is absolutely nothing showing on my bank statement. I cancelled an order on 25 November and then called in and spoke to a lady by the name of Melissa from the online order platform. She had advised that it would take 7-10 working days. We are now at 13 working days and they STILL have not paid me my money back. What *** is this? STOP trying to convince me that my refund has been done. I know how to read my bank statements!