First check your order details for the item, your email and even Spam in case it was sent there.
If not , you do need to contact eBay Customer Services. Be aware, you have 7 days to collect your item, after being informed it's in store.
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.
@mireilloyewol0