How can I get Android 4.0.4 on my XPERIA Neo V?
You might want to visit the Update page for Neo V for closer information on how to update. It not only tells you what has changed, but also provides you with the required downloads.

The link is to the UK version. I could not find any link for Argentina, and the Brazil page does not even list the Neo V. So you might want to check around for yourself -- at least that's somewhere to start with.