Question: Bus from Buenos Aires, Argentina to Temuco, Chile

We're going to the United Nations Framework Convention on Climate Change in Buenos Aires, Argentina this December. We have a campaign that relates to climate change and stopping genetically engineered trees. We are leaving Buenos Aires around 17 December via bus to go to Temuco, Chile to meet with Mapuche indigenous activists. We need to know some sort of a bus schedule from Buenos Aires to Temuco so we can set up a the meeting as soon as possible from here. Also prices? We also would like to know if there is a place the bus stops in the Andes overnite or if that is an option.