What are my rights when a concert is canceled?

I bought 2 tickets to Elton John on 8/2 and they canceled that show. They are going to credit the concert tickets but I purchased 2 non refundable airline tickets. The only reason I bought them was to fly to see Elton John and now I don't get to see him. I asked the ticket vendor to compensate me for the tickets and they refuse. I have asked them to provide me doentation that states that on their website and they have refused. Help