No delivery

I ordered two items on 2 January and paid for both. One item was delivered, the other was out of stock. I asked if I can change it to something else. I even sent the links of 3 possible items to replace it with. It takes days for Lynn or Noreen from Customer Care to answer my emails, and no one picks up the phone. I have been informed by Noreen on 25 January that my replacement order has been processed, but I haven't received anything. On 5 Feb Lynn sent me an email that on their system it shows the item was delivered, but that is not true. What more can I do to get my item delivered or my money back?