My client refunded without any reason

I recently sold my item to a client and he stole my item and selling on another site for 90% off and Envato did nothing.

And now this user refunded his money, where is the justice now, Envato so doing nothing instead Envato refunded his money though selling my item on another website.
Why Envato’s helping him to stole my item and refunded my money. I don’t understand here, It’s not from fair!!!

Who can help me? Where should i connect? Please help me!

I’m guessing it was a sale reversal rather than a refund? It will say in your statement. Envato cannot approve or reject reversals, they are processed automatically by the payment provider.