Remember that the seller ships to the GSP plant in Kentucky, who re-ship to you.
So ask the seller what company he used and where he sent the parcel.
There is a poor soul in another thread whose seller listed the GSP as the shipper and then shipped directly, causing all sorts of confusion and expense.
While you can't open an eBay Dispute until the last estimated date for arrival has passed, you can open a Paypal dispute for 180 days from PAYMENT.
But get the shipping company first. It may just be a spacey seller.