Check your order details, your emails and even Spam it might have ended up there.
If not in any of the above, you will need to contact CS again , but I recommend do so only very first thing tomorrow morning when the lines first open at 8 a.m. as there's more chance of Dublin answering and perhaps understanding more the importance of that code, than someone in the Philippines.
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.
As said, I recommend contacting CS first thing in the morning as there's more chance of Dublin answering.
Remember, you have 7 days to collect your item, after being notified that it's been delivered to your store.
@brian9291