Nature's Miracle is very good, and cheap. It does require some rubbing, not a lot though.

What are you doing to prevent accidents? Is Charlie crate-trained? We've prevented our new puppy from having any accidents, using his crate and x-pen, and very frequent trips into the backyard! He gets to go outside every time he wakes up/gets out of his crate or x-pen, shortly after eating/drinking, and other than that every half hour or so. Until he gets the hang of going OUTSIDE, you need to over-do it to encourage him. Potty pads around the house might also prevent your carpet from getting ruined.