The confirmation email you received from Ebay should contain the links for opening a not received case, BUT if you are now past the 30 days, too late for any action through ebay.
When you buy as a guest, it will not show in your purchases, and seller does not know you as ercald_9310, so any action which you take has to go through the email route. Contacting seller direct, he will have no idea who you are, so not surprisingly does not reply.
As you are now too late, suggest contacting your payment provider, to see if they can help.