You can ask a seller to cancel an order, but they do not have to.
If the seller does not cancel the order and refund you after 7 days, open a case for item not received, escalate on day 4 if not refunded beforehand.
If there is difficulty opening a case, then contact eBay Customer Services.
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.
@michaelburkey2011