Scammed by seller and support giving bad support

Hi, 18 days ago i bought hurtworld , i received a key that was already used , i notified the seller , he said that he ll speak to humble bundle and steam support blah blah blah. I set the transaction to under review because the key wzsnt working , the support completed alone the transaction , i sent a lot of messages to the seller but no answers and support gave the 14dollars to the scammer! Next i opened ticket and support said i received an answer from them about the purchase, it s a lie , secondly support said that because the transaction is complete he cant do anything and i need ro speak with the seller!!! WTF seller dont answer and support screwed i need help i lost my money and this scammer can use it

Did you rate the transaction?

No the system automaticaly rated it for me to positive , yuk