How do you file a complaint with the App store?

Does anyone know how to file a complaint with the app-store people? This may sound really childish but PlayFirst has a series of games called Dream Chronicles available in the app store. They're listed as free then in the description they tell you of course you can "try it free then download the full version from inside the game". Recently they released Dream Chronicles: The Eternal Maze available for "free" in the app store with no mention of the "try it free then download the full version from inside the game". It may be petty but I consider this false advertising since their other games tell you it's not the full game.