I went to Buenos Aires in a Spanish school and booked the flat for a month. I liked it there. The flat is nice and roomy, has a large balcony where you have a nice view over the city, a good equipped kitchen and a washing machine. San Telmo is a good place to live. Close to the downtown where my school was placed (walking distance), has a lot of cafés and restaurants in the neighborhood and is close to other parts of the city.
The contact to Florencia was pleasant. She replied to my mails immediately and was very helpful. She also organized a taxi from the airport to the flat witch i found was very convenient.
A older lady welcomed me at building and showed me the flat. She doesn't speak English but somehow it worked well.
Thanks Flor, I enjoyed it.