Please see this info, Alondra, that I found at the state's department of education website, http://www.fldoe.org/classsize/. You will see there language around class size for FL schools.
As for a complaint, I would begin with someone at the school and then, if you are not satisfied, move to someone who serves on the school's board, since the board governs the operations of the school. Next I would go to the school's authorizer, which I am assuming is Miami-Dade Public Schools. You will find the charter office of Miami-Dade here, http://charterschools.dadeschools.net/.
Good luck - and I have left the link to my website below. I am a long-time K-12 educator who wants parents to have the best info possible about schools and school districts.