I concur with the above expressed concerns. I had to fly from Lima to Cuzco Peru. The travel agent only had access to 2 airlines: Lan Peru and Taca. However on arrival at the airport, I discovered 5 airlines flew the routes and their fares were much cheaper than what I paid. Having never before been to South Amserica (I live in Australia) I would not have known it by then, even with my strong interest in aviation and timetables.