As long as you follow the process, and go back to the case to ask Ebay to step in after 19th, you should be refunded.
Unless the seller has tracking that proves delivery to you, Ebay will find in your favour.
"There are two ways to be fooled. One is to believe what isn't true; the other is to refuse to believe what is true.”
Søren Kierkegaard, Danish philosopher (1813 - 1855)