Pre-orders should only be sold by business sellers and Ebay have limits on how long sellers can make buyers wait.
You need to find the email you received from Ebay when you placed the order and paid.
What is the latest estimated delivery date on that order?
If it is less than 30 days ago, you should open an 'item not received' case as advised.
Otherwise, you will have to try your payment provider.
Pre-orders do seem to be a highly effective way of unscrupulous sellers getting money for items that are never sent.
You can report an item not received using the button below:
Report item not received
"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)