Hon is right it is above scotia bank acroos from tropic air. Don't wait untill the last min. as you have to go to a few didderant places first to the immigration office then another place to pay then I believe back to immigration. This is what I was told. Also they are closed between 12p and 1p good luck and if you still can't find it just ask people are more than happy to help here.
They have a new twist......they only give you one copy of the invoice.....you need two......so before you go pay to have to get a copy from a shop across the street from Wings.....then go pay.....unbelievable!!!