I have experienced various issues, like unannounced substitution of similar items, no-delivery, and sellers cancelling orders. In every case so far, ( I use Paypal ) whenever the seller didn't already refund, Ebay has refunded the purchase price.
BUTThe long delivery windows specified on most of these items from India and China means that for any issues related to fulfillment, one needs to wait until the END of the delivery window to get resolution. If the seller claims that delivery takes from 10 days to 2 months, I wouldn't bother asking Ebay to resolve issues until the full 60 days have passed. You can complain directly to the seller, but I wouldn't anticipate a lot of satisfaction coming from this.
What you described, 3rd party fulfillment, is standard operation procedure nowadays. It's common practice on Amazon and with various other internet sales sites, including Ebay.
I have posted previously, and complained to Ebay, about what I call "the long delivery window scam", which I think works as follows:
1) Seller offers an item with a wide delivery window, like between 3 weeks and 3 months.
2) Delivery routing information shows "shipment number reserved" or something like this. Foreign shipping companies/ post offices are very opaque. This status qualified in the Ebay system as "item shipped", now the buyer must wait. Has the item actually been shipped? Maybe, but who can say.
3) If you enquire, seller says, "wait". You must wait the full 3 months before Ebay will act on your behalf.
4) After 60 days, the sale drops off your Ebay front page, the information is still there, but it's not in your face.
5) At 90 days, buyer loses the ability to leave feedback. Negative feedback is about the only effective tool to discipline bad sellers.
6) If you complain, seller can cancel the transaction, and refund your money at any time. The transaction "disappears". Buyer can't leave feedback on a seller-cancelled transaction.
7) If you complain, early in the wide delivery window, seller can easily send a 2nd shipment and still meet the WIDE delivery window.
If you don't complain, seller keeps your money. I suspect that a good percentage of buyers don't complain. After 2 months, they have forgotten about a $7 purchase.
The cheap prices come with a cost.