Raise a complaint against seller

[sureez]

I bought a product from a seller and that product has 6 months seller warranty. I sent for the replacement by contacting seller via message. Now he is not responding my phone call and email. I trying to reach him for last 2 months. now i dont have replacement/refund and i don't know what to do next. i raised a complaint in customer support in "Report a member" option but no reply from ebay as well. How could i trust ebay if it is not taking care of this issue. Please advice me what to do