Leave it for a few days then you should be able to select "Report an item you didn't receive" on here:
https://www.ebay.co.uk/help/buying/returns-items-not-received-refunds-buyers/get-help-item-hasnt-arr...
and escalate it 3 complete working days later to get a refund.

If you have any problems with that contact ebay about it.   You can ring them or request they ring you by viewing this link on your phone - not on a laptop or PC:
https://www.ebay.co.uk/help/eua?id=5190