Take my comments with a pinch of salt, because I don't particularly like Madonna (not her music, I like some of her music; I just think she has a terribly overinflated sense of her own talent and importance), and I'm struggling to put what I mean into words...
President Banda's letter sounds generally fed up with a unreasonable demands leveled by a rich famous pop star breezing into the country (uninvited, so basically like every other normal tourist who visits there) and demanding special treatment just for being there.
Complaining about having to check in at the airport? Everyone has to do that, except possibly the royal family and country political leaders, neither of which Madonna is, despite what she seems to think of herself.
Building schools (or class rooms, or what ever she did build) while a very admirable charitable act (and kudos to her for doing that, despite subsequently trumpetting those charitable acts from the rooftops, which leaves a rather selfserving aftertaste to her charitable actions), does not entitle one to the royal treatment everytime one returns to the country.
As resident of a nearby African country myself, I can sympathise with President Banda's irritation. I also get irritated by famous rich people trotting in to toot their own horns about how wonderful and generous they are for charitable actions, for what seems to us locals like they're using other people's poverty as a backdrop to make themselves look good. By all means, build schools, build orphanages and so on, but do it out of genuine charity, donate the money and then keep quiet about it, without having a press posse follow you around to show the world how awesome you are.
Then again, the improvement in people's live brought by those self-serving donations are still so much better than no donations at all.
Ettiquete-wise, noone comes out smelling like roses. Madonna had unreasonable demands that just show how inflated her own sense of her importance is in the grand scheme of things. I also think President Banda's letter is blunt to the point of rude, but it still voices a common sentiment by those of us who live in the countries whose people can end up feeling like they're being used as wallpaper to other's PR exercises. I'm kinda on the president's side in this thing.