Look into getting your child into another school as it sounds as if the school is not in control of what is happening there, why have not got more supervision in the Play ground and taken the resonsibility, can the parents take it on to go in turn and supervise?Take control with the other parents they are your children protect them whatever it costs or get a better school.
this will sound harsh but you have to let it go
what do you WANT the school to do that they have not done?
expel the students that talk about anything remotely sexual?
close the school down?
have a meeting and keep discussing it more and more?
your concerns are starting to make you so emotional, sounds to me, that you could be talking this up so much your daughter could end up suffering more than she ever would have.
I am sorry this has upset you so badly but get along with your life- you made your point maam- now try to get a bit more positive about your daughters' school.......force yourself to stop it- can you tell me honestly that your daughter is not affected by all the uproar? I can just imagine the gossiping, the whispering, the phone calls, to keep this stirred maam- 3 years?
If you really dislike the school so much, put her in private school and get happy.