Hi I know this has been discussed before but Im trying to make sure I get it right?Just got prices for june for bali would LOVE to do business class but whoah those prices are a lot more than economy.I read somewhere that you can pay to upgrade when your in bali for return trip only?can you do this when you arrive in bali for coming back or must you wait for last day?and approximately how much?And do you do it at their office of the airport appreciate any help?