It's NOT Post Office tracking. There's no such thing. It's Royal Mail Tracking. The Post Office and Royal Mail are two separate entities.

That tracking number you provided shows that Royal Mail are waiting for you to post the item. Nowhere does the tracking result show that the item was ever delivered. The item is marked as "We're expecting it" as soon as the label is generated. Had it been scanned at a post office counter this would have changed to "The item has been accepted at... "

The only proof the buyer has the item is that you say they have. You didn't say, when asked, whether you received a proof of posting receipt when you handed the parcel over at the post office counter. You have, however, provided conflicting information regarding the cost, and the method the item was sent. First eBay charged a fiver for postage, then you said you paid £32 for a registered parcel.

Also, just for clarity, this is a public forum, you aren't talking to eBay customer service. We're regular members of the public, like yourself. Only community team members like Marco work for eBay.