You're absolutely right DWKWIA - far more stress than it's worth. I only bothered after talking to a friend in Bogota about it who told me in advance that LAN would do everything possible to avoid refunding the tax. Turned out he was right! That kind of thing irritates me as it's totally illegitimate behaviour. Every other airline ex-BOG manages to do right by their passengers - why should LAN have it differently?

BA eventually sorted it out for me once I got the right person on the phone, although the agent told me that it took the refunds department a while to track down the tax and extract the money from LAN themselves