Paid for goods I've not received

I placed an order with Zando on Dec 2 and proceeded to track its progress online. I received an email on Friday, Dec 4 saying that my order was en route, and an email on Dec 5 saying that my order had been delivered. I immediately sent an email to Zando stating that I had not received the order and querying what was going on. I never received a response to that email. I called on Monday, Dec 7 to inquire and after a long wait on hold was told that the courier had mistakenly marked the item delivered. When I asked where the parcel was or when it would be delivered, I was told that someone would call me back with that information. No one called back. I called again (Tuesday, Dec 8) to inquire, and after an ever longer wait on hold than the previous day, was told that no information was available about my order but that someone would follow it up and call me. No one ever called. I tried calling again on Wednesday, Dec 9 - during the customer service hours listed on the website - and got a message that the office is closed. What on earth is going on?! I have paid for these goods and no one seems to be responsible for actually ensuring they get to me.