The seller's name will probably be removed from your post, because we are not allowed to 'Name and shame' members. This may not apply to NARU members.
Go to the Resolution Centre at the bottom of this page. Try to open an Item Not Received dispute. This may not work because the system automatically includes time for delivery.
Go to Paypal and cancel your payment. It may already have been claimed by the seller,though.
Phone eBay through Help and Contact at the top of this page. Do this after trying the robot systems which are usually faster than the human -based ones. Bring a beverage and a good book and pee first. You may be on Hold a lot.
This may be something of an exercise in frustration, but you will eventually get your money back.