Who closed the case?
The seller can't, but it will time out.
You have probably done your dough, unless there is no tracking, in which case a Paypal case should be possible.
As jellybird said in another thread, why would you believe a seller would send a replacement when they didn't send the original item?
For future reference, never let a seller string you along (especially if they are not registered in Australia).
If they offer a replacement and don't upload valid AUSTRALIAN tracking in a couple of days, don't believe them.
Go for the refund, as that is all the eBay Money Back Guarantee covers.
You can always repurchase after you've been refunded, preferably from a different seller.