eBay should treat it as delivered, but with such a high dollar item, I have no idea if they would. Do not refund yet, some people try to get ahead of the game and refund, I have no idea what your eBay experience is, so do not refund yet.
If I were in your shoes.........I would contact the post office where it is being held, immediately. Go to the USPS site and find the post office for that zip code, then click on that location to get the LOCAL phone number for it, don't use the 1-800 number. Call the local number and ask to speak to the post master (or whomever is in charge at that moment) so you can be sure that you are able to recall the package. You will have to do the actual package intercept online, but I would want to make sure the post master has it in their hands to prevent another delivery attempt because the package intercept is not guaranteed.
If you refund before having the item back, they can just go pick it up at the post office. If you lose the payment dispute, there is no guarantee that the package will have to be returned to you. So I strongly urge you to call the local post office number of where the package is and see what you can do to protect yourself. Do not wait, scammers spend lots of time working on their scam, they may have been successful previously. I would start calling an hour before the post office opens for business.
For the dispute, make sure to upload your "evidence" which would be a copy of the order details showing the address and hopefully a copy of the shipping label, as well as the tracking history from the USPS site. You may have to put those things into one .jpg or something to be able to have it all there, I am not sure how many items you can upload for evidence, so make it easy for them to see the facts.
Best wishes.
