Will not send refund--avoiding responding to emails, requests for refund

Sent back a portion of my order on Oct 3rd. Sent an email on Nov 23 to check the status of my refund. I included the Delivery Confirmation tracking # showing that they had received the package/returned items on Oct 5 at 10:33am. Received an email on Dec 3 requesting the same information despite they had replied to my email with the information in it. Resent another email December 23rd. Still no refund, no reply.