AX9465 - assuming you are only needing 4 flights in total then I would say purchasing individual flights would make better sense (especially if you book a long way in advance as previously said). Book far enough in advance and you might be able to grab flights from around $45 USD each!
Pantanal - Mercosur is now a subsidiary of TAM so I would guess that their airpass would have been folded into TAM.s