You should check with the Member who should have sent the item that they did send it and that they have the Proof of Postage document.
Either you or the Member who posted the item will need to make a claim from the Post Office using an Inland P58 form. You can download a copy of the form here
You will need the co-operation of the Member you dealt with – either to make the claim on your behalf or to securely send you the original Proof of Postage document so that you can make the claim.
If you are making a claim for compensation you will need to enclose the original Proof of Postage document (not a copy) and a copy of your Paypal account or other confirmation of payment and purchase price.
Please provide the other Member with copies of all correspondence. In the event of compensation not being obtained from Royal Mail for any reason, the buyer can always fall back on making a claim on Paypal.
Playr2 cannot get involved in any disputes of this kind as the service is provided free of charge. However, you can leave Member feedback, but please remember to keep it factual.