I don't know, but it's a good idea to check the actual rate that they are handling at http://www.bna.com.ar/ and then compare it with the one at xe.com .. they used to be the same last year, but God knows how is it right now
Most of the Banks down here do change a comission, specially in the airport. I suggest you to go downtown and exchange big sums there because banks in airports usually charge a lot of money out. Felicity-