LAN have different award levels, only the lowest will be available for OW Airlines (AA, BA).

1. Create an account with LAN (LAN Pass)

2. Go to LAN.com, where it says Flights, select LANPASS, enter Buenos Aires and then Bariloche, select your dates, click on search flights, then it will ask you for your User or LANPASS number and your password, the result will give you different awards levels, the lowest price for BUE-BRC is 28.000 Kms, if you see it online, AA or BA (over the phone) should see it too, but in the last few months, LAN is not releasing many seats to their partners (AA, BA etc).