If you made two orders, then 2 cases needed to be opened not one.
Are you still within 30 days of that order's last estimated date for delivery? Then, open the relevant case for that order. When you say the seller is no longer on eBay are you seeing ' Unregistered seller' ? This means eBay have removed the seller from their site, and you do need their help opening that case.
I know you have had issues with CS understanding the problem, but I strongly recommend contacting CS first thing when the lines open for ' live agents' 8 a.m. on weekdays and 9 a.m. on weekends, as there's more chance of Dublin answering, only speak to them. It's a Call Back option so you'll hear if it's the dulcet tones from the Emerald Isles.
This is the easiest and quickest way to contact eBay Customer Services, for a Call Back option.
https://www.ebay.co.uk/help/eua?id=5275&mkevt=1&mkpid
Lines open 8 a.m. - 10 p.m. on weekdays
9 a.m. - 6 p.m. on weekends.
Automated agents will be available on chat outside of the above hours.
I recommend contacting CS first thing in the morning as there's more chance of Dublin answering.
If the 30 days have lapsed you will need to turn to your payment provider for help with that refund.
@krla_279