What if you send a game back to Gamefly, but they never receive it for more than 7 days?

I sent this one game back 6 days ago, and they still didn't send me another game, but they assume that they have never received the game. Please tell me this, are they gonna charge me on my credit card, or are they gonna send me another game if seven days has passed. Please tell me how this company works, and how are they gonna solve this problem. Even know I sent them a shipping problem, which I already did.What if you send a game back to Gamefly, but they never receive it for more than 7 days?their is a place on this site i think its under account options it lets you report that you sent it back but they haven't got it than they send you another and they don't charge you