Getting to the heart of things

Last week's Spanish homework was to write a letter of (imaginary) complaint. My teacher upped the stakes - not only was I to (try to) get the grammar right, I also had to persuade her that I had indeed been wronged and deserved recompense. But - and here's the point of my post - the way to persuade in Latin America isn't to get mad or threaten legal action: it's through emotion. The approach would be the same if you were writing to the CEO of Chile's most prestigous company - you need to wring their heart, persuade them that your grandmother's life has been threatened by their negligence, that they have made your orphaned nephew cry himself to sleep, that sort of thing.