If it failed there is no way they can get your money. You should check in your game account to see if the game isn't in it or your gaming library. If your bank account is charged the money or your credit card.
Then the transaction should have gone through. But if your accounts show no activity then you are ok. When a electronic transaction fails nothing get past. Unless you got routed to a fake Steam site and they rip you off.
But I doubt that. Another problem could have been you account in your bank didn't have enough funds and that caused the transaction to fail and the missing money is a over draft fee.
I hope that isn't the case but get hold of them if you can't find the money or the games. I wish you good luck on this. Here is a link to there support. https://support.steampowered.com/