I have buyer protection.
Let's hope you do. As you have discovered, eBay's initial response is that if it's tracked as delivered, it's been delivered. We often hear that eBay has placed the onus on the buyer to prove incorrect delivery. Unfortunately, they don't take the buyer's unsupported word for anything - not even that the photo to prove delivery isn't even their address!
It's hard to help with so little information. Does the tracking record confirm the address or even postcode to which it was delivered? Even if not, your friend at the sorting office may be able to give independent confirmation that it was not delivered to your address.
We don't know wherther this was a business seller or a private seller, who would probably have used eBay's simple delivery system. If so, it gets very complicated as eBay would be responsible for refunding for loss in th eost, but the seller would be responsible if it was proved that the item enclosed was not as described.
You will need to start by opening a case under eBay's money back guarantee. If the item was lost, or never reached you, you would open an item not as received case. But if the packaging (with or without the ball pen) reaches you you would open an item not as described case.
Good luck, and be sure to keep copies of all docuents and web pages. If eBay won't give a refund you may have to try your payment provider, e.g. credit or debit card issuer.
Buying from strangers on eBay is not without risk, especially phones. For example, did you realise that eBay's money guarantee can expire before a phone is reported as stolen, and is locked or blocked. But after 30 days, no buyer protection from eBay. If you wish to buy a phone here it's safer to stick to well established phone sellers with plenty of good feedback.
