I have the same issue. My order also said Deliveried, by OnTrac, on 01/11/19, but my order was nowhere to be find.
I contacted Zara 3 times in total, as of today 01/31/19. The first agent took my informations, and said that they will open a case to investigate more; the second agent told me to give them my information once again to create a case for my missing order. I was shock to know that Zara did not open a case for my missing order when I first contact them. I waited 2 weeks and have not heard anything from them nor recieved any email to let me know about my missing order.
I contact them again today at 3:40a.m. Cali hour. The third agent, asked me about my information again!!!!!
I asked the agent about how long will the case take, the agent told me that Zara cannot estimate the time to solve for my missing order. My order was about $560, and now I have been charge for something I did not recieve, and they told me they do not know how long the investigation will take.