Firstly, apologies if this is in the wrong area.

I have booked a domestic flight in Peru on LAN using my using my FF points. Being aware of the non Peruvian charge on LAN I asked the Qantas representative if I would have to pay the extra charge as determined by LAN. He believed that all should be alright. To be safe I contacted LAN and the person I spoke to knew nothing of the extra charge and so I tried to explain it to him. I think to get me off the phone he ended up saying that the amount was a charge enforced by the Government similar to a Value Added Tax.

My question: I travel Bogota to Lima on LAN where after 4 hours I have the domestic flight to Tacna. I am unsure if I can check the luggage all the way through but do I still have to pay the additional US$178?. If I must pay it will still be cheaper for me to purchase a ticket on Peruvian Airlines so I need to weigh up as to whether or not I cancel my FF purchased ticket. Thanks for any guidance on this.