If you are still within eBay's 30 day MBG period, then open a case in the Resolution Centre, link at bottom of most pages, for item not received. Escalate after exactly 8 days and you will be refunded.
Do not close the case early on any promise from the seller for a refund or replacement, once closed it cannot be reopened. Let it run the full 8 days, and if it is not resolved in that time, do not forget to escalate.
If you have gone over the 30 day time frame, and you paid with Paypal, you have 180 days to open a case with them.
