I can provide some great advice here. I am an avid eBay-er and have run into this a few times.
https://www.ebay.com/help/buying/returns-items-not-received-refunds-buyers/ask-ebay-step-help-buyers?id=4701
Start your process here, if it rejects you can go directly to your credit card company. Have your tracking # for return ready and they can usually do a full refund with proof of delivery on that tracking #.