There are proper procedures to follow, it is on every listing, on the right something like BUY WITH CONFIDENCE.
Buyers can only ask sellers to cancel, but if you receive nothing you use the, Ebay 30 day money back guarantee and open a not received case. YOU CANNOT RETURN AN ITEM YOU HAVE NOT RECEIVED.
If you receive the wrong item then you open a NOT AS DESCRIBED CASE, and seller has to provide a return label and on return refund.
This is all covered in the ebay 30 day money back guarantee, but as you are out of time, contact your payment provider.