First of all, try sending the seller one final message via eBay Messages saying something along the lines of "I have tried contacting you [insert number here] times so far to arrange a mutually convenient date and time to collect the item and to obtain your address so that I know where to collect the item from, but so far have not received a reply. Could you please provide me with your address and a date and time that would be suitable for collection so that I can come and collect the item?"
Once you've done that send the message to the seller. Given him/her a maximum of three working days to respond and if you have still not had a reply after the cut-off date that you decided upon open an Item Not Received case with eBay. If you still don't get any joy from the seller after doing that then escalate the case to eBay four days from the date that you opened the case. Once eBay review the case and see that you have made numerous attempts to contact the seller to obtain his/her address so that you could collect the item, only to be ignored by the seller every single time, they will more than likely refund your money in full.
If you do decide to take this advice and eBay do end up having to force through a total refund you will no doubt end up on the seller's Blocked Bidders List, in which case you will just have to search for an identical item being sold by a different seller and hope that the second seller doesn't waste your time in the same way that this seller appears to have done.
