Seller does not accept return after writing him about it on ebay

I bought a computer for my 1993 Jeep Wrangler and was not able to send it in on time because I had to take it to Costa Rica to show the mechanic. I wrote the seller back on E bay and he assured me it was alright to send back on later date. I did not have the mail print out tag so he sent me his mailing address and i returned it and paid all the mailing. Now I have not heard from the seller. Evecchiomotors.........I have full account of letters written through E bay...HELP !!!