I think the social media is contributing to the increasing awareness of businesses of the need to keep their customers happy. As what @Decentlady noted, some battles are worth fighting while some aren't. If the amount is too low and if it would cost me more to go back to the store to complain, I'll most probably just charge it to experience. But if the amount is big and the item is that important, I'll probably take the time and the effort to complain. Sometimes, I would feel the need to complain just to teach some people a lesson. In fastfood joints, for instance, not only are the staff trained to put more ice than necessary on the drinks, they are sometimes too lazy to fill the glass to its full capacity. I would always complain and ask the service staff to max it. However, I am also not like some people who would complain for the sake of complaining.