What would happen if I sent a complaint/question to a business ?

I recently read a book that talked about the FDA ,FTA, healthcare, pharmacys ect. It says basically that they are ripping us off. But anyway I was thinking about writing a email to Johnson & Johnson (a big drug industry) about how enraged I was about what they were doing to people because of greed for money!! I know it sounds stupid but I can't help but feeling angry at them. If I did what would they do? Would they just write a reply? Would I get in trouble? See, the thing is, I'm only 13 /: