OP: I can feel your pain.
I am going through EXACTLY the same crap with eBay right now.
They made we wait until the end of the expected shipping date range completed, (from China), even though the seller is no longer registered!
Then once I filed the complaint, they made me wait a week "for the seller to respond".
HOW THE HELL IS HE GOING TO RESPOND WHEN HE ISN'T REGISTERED???
Then at the end of that week, I was finally given the opportunity to tell them that "I could not reach an agreement" with the now non-existent seller.
Now for the past week, I login to see "Hang on, we're still reviewing your case. We'll be in touch with you soon".

I have no confidence eBay is going to do the right thing, because the last time a seller sent me a piece of junk, and was suddenly unregistered, eBay response was that because the seller had sent "something", then they considered it a valid purchase. Morons.

ETA timeline:
Oct 16 purchase
Nov 16 filed initial complaint (told to wait for seller response)
Nov 22 filed second complaint (could not reach agreement with seller)

The purchase price is low, and I fully expect to lose the money, but this is only the second time I've had a seller unregistered, so I view it as a cost of doing business on eBay.