If you post in Discussion > Selling or Discussion > Postage you will receive a quicker reply.
In case it helps you or other Sellers, I'm untangling your money logic here:
- Item is lost by the courier, so you're missing the item.
- Buyer gets a refund in full, now you are missing the item and the postage cost.
- You make a claim for the sale price of the item (using eBay invoice) or original price (using receipt) plus the proof of posting.
- You are paid by the courier for the item and the postage cost, so you are not missing anything!