Wkitravel´s comments are right on:

I have lived in Mendoza for 4 years, and am familiar with all three schools listed.

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"As with many cities in Argentina, there is a variety of Spanish courses and private lessons are available. There are two extablished language schools in Mendoza: Intercultural [7] is the biggest, has a range of afternoon activities, and is slightly more expensive, Greenfields [8] (aka COINED) is smaller and feels even less well organised, but many of the teachers work at both schools.

Another great option for individual or very small tailor-made quality group lessons with a highly trained instructor, Ana maría Troncoso: Spanish in Mendoza, Argentina (SIMA) [9]. This is a better option for those seriously interested in learning or improving their Spanish, although the classes are very enjoyable. http://spanishinmendozaargentina.greenash.net.au/"