Within 30 days after delivery, go to your Purchase History, find the item, and under “More actions” click on “Return item” and select the reason for the return. “wrong item received". Attach a photo.
The seller will have 3 business days to either accept the return and provide a prepaid return shipping label OR refund without having you return the item.
If they don't do either, you can go back to your Return Request details 4 business days after you filed the Request and ask Ebay to step in.