The Sao Paolo gig will be in the exact same date of ENEM (24th October), a national exam made by millions of students of age around 15 and 20 mostly.
This will lower the sales by 20% at least, I would say. Only in the first day (25th May), half a million brazillians have already subscribed for the exam. This weekend, 24th October, is absolutely focused on ENEM. The whole country goes on and on talking about it.
Again, it would be wise to change the date.
Contact anyone and everyone you can about this. Maybe we can reach the responsibles.