User Moparofficial not responding..

So I purchased a NOS Valve Cover from user Moparofficial. The AD said the chrome cover was for a Slant 6. Being that we are on a A-bodies web site. I figured the cover would fit my Duster. Right after I sent the money to him, I found out it was correct for a 80's Slant 6. I would have never paid the amount I did if I knew this, and Moparofficial did not reveal it in the AD. I notified him quickly, and he refuses to respond to Phone and text messages even though he gave me his number prior to the sale telling me to call if I had any problems. He is also ignoring messages I sent on this site. What would you do??