What's My Name?

I've been in this town for over six months now, and the volunteer (Charlie) who was here before me left six months before i got here. So a full year has passed since this guy has been here, with a six month transistion of no Gringo being here. So why do people still consistantly call me Charlie? At first I was polite bucause I realize just as we think all latino's look alike, they think all white people look alike. But now I've started getting rude cuz, c'mon a full year has passed and they can't figure out that I'm a different Gringo living in their town of six thousand people and one white person.