If the seats are truly scuffed then the dye has actually been abraded off. No simple leather cleaner/conditioner in the world is going to fix that. The situation is not all that different from sanding paint off a fender - you don't apply a coat of wax to fix it.

There are auto upholstery places that do a fine job of dying leather, and others that are a total waste. The trick is finding a good one in your area.