"I have jsut spoken to Royal Mail and they have advised for you to wait 15 working days and if the item has still not been received to then download a claim form from their website and claim your money back. This is Tracking Number: ******** I have entered this code into the R.M website however it says the item has not yet been delivered"
I sell a lot on ebay. I'd advise you to wait til the period had expired, then I'd refund and process the claim for you.
BUT I would ask you to check your local sorting office, cos a few of my recent 'lost' parcels have turned up at the local sorting offices. The post office just seem to miss leaving cards over Christmas.
Once you've done this, you've done all you can. I'd say it's down to the seller to refund. They have an obligation to do so under Ebay rules and if you've paid by Paypal, you can claim back through them.
I'm fairly sure I'm right, but I'd check the Ebay buyer protection, just to be on the safe side. Hope you manage to sort it successfully.