Yes, you can send it back as the only way to see if the item was fake was to open the pack and check the cards, so just proceed this way:
If you are still within 30 days of the item's last estimated date for delivery you are guaranteed a full refund, under eBay's 30 day MBG, Money Back Guarantee policy, as you have received an item not as described, go right of the item in your Purchase History and from More Actions select... Return this item selecting the reason Item Does Not Match Description or Photos.
The seller needs to accept this case within 3 days and refund, if they want their item back first , they need to pay for that fully tracked return postage, then on receipt of their item they have 48 hours to refund you. If they don't , need to escalate the case, ask eBay to step in, and they'll force the refund.
Never listen to any excuse or promise from the seller to close the case early, and do not forget to escalate.
The seller may well claim the item is being sent back opened and so in a different condition, but here you have a very good case to argue against, if your refund is refused, you contact eBay Customer Services to explain it had to be opened to check.
Keep this link to CS below, in case you need it later:
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.
@heyit_1197
