Help please on holidaty visa! (São Paulo)

Hi Guys!

i'm currently in Sao Paulo on a holiday visa like many gringoes and I was hoping someone could shed some light on a issues I have as few people seem to know the rules and regulations surrounding visas.

So I want to stay longer than the three months, Can I renew my holiday working visa for another 3 months without leaving the country.
Or if I don't renew it and stay past the 3 month deadline, how much am I fined and what are the implications of this also.

Thanks guys for taking the time out to read this.

John