The Ebay code is a VTN (virtual tracking number) and doesn't mean the paarcel can be traced to the sender.
If there are no sender details, there is not anything you can do.
I would keep it for a while and then dispose of it.
Is it a low cost item?
"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)