You are not talking to your seller here, but to other members like youraelf.

On your Purchase History go far right to More Actions,  from there message the seller and report your findings,  only they can speak to the courier.

Do not let the seller time you out with excuses if they have sent the oder to the wrong address, that is, not the one eBay provided for them on the delivery order,  then you can claim a full refund.

Go right of the item purchased,  and from More Actions select....  I Have Not Received My Item.

If you are not fully refunded within 3 days,  you must escalate the case on day 4 or within 30 days from opening the case,  and eBay will step in and force the refund.

Do not close the case early for any excuse or promise the seller may give,  and do not forget to escalate.

Make sure your delivery address is correct in your eBay account, if the seller has to posted it there,  and has tracking to prove this,  they will not have to refund you.

Check your address is correct here:

https://accountsettings.ebay.co.uk/uas/addresses

@moham-faru