Learning Spanish in Mexico - recommendations?

I'm looking to travel to Mexico in December 2011 / January 2012 and would love to hear your recommendations for Spanish schools. I'm probably about intermediate level, having been learning for just over 3 years now. My wish list:
- in a great beach area
- possibility of some volunteering work
- opportunity to meet other travellers (I'll probably be on my own)
- South of Mexico City

I've looked on Google, and at the Lonely Planet listings, but would be really keen to get any recommendations from other travelbloggers.

Thanks in advance!

Rachael Reply to this