It is possible you don't need to speak to anybody.
When did you pay for the item?
Check the latest estimated delivery date - that will be on the email you received from Ebay when you paid.
One day after the latest estimated delivery date, you can use Ebay's automated system to open an 'item not received' case.
"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)