My family in Argentina! I had a wonderful time at Hotsel Colonial in Buenos Aires!
The owners Fede and Kevin are pretty helpful and friendly and the volunteering work schedules are pretty flexible, so you'll have plenty of time to get to know te city and it's people!
The work consists basically in recepcion work and cleaning/organizing the hostel. I stayed there for three months in total and I made really good friends there!
If you choose Hostel Colonial to your next volunteering trip to Buenos Aires you'll wont't regreat! I garantee you =)