Xenophobic, Awful Remarks!!

[user1483893543]

My twins are turning 13 later this month.
They've got a friend who hosted a party at a trampoline club, so I let them go. I dropped them off at the place at around 1:45 and picked them up at 5:00. When we got home, my daughter started crying, which she never really does. I asked her what was wrong, but she wouldn't answer me, but my son (my twins are male and female) told me that the girl who hosted the party kept on hitting my daughter and making xenphobic remarks (I'm half Cuban). My son also said that he stacked up for his sister but the girl just started on him, too.
When I eventually got something out of my daughter, she said that this girl has picked on her the entire school year. I was like, 'then why the hell did you agree to go to the party??' and she said that the girl threatened to kill her if she didn't turn up.
I'm so mad at this situation, I've went into the school and asked to speak to my kids' registration teacher, and she just said it's 'child's play.'
What do I do??? My daughter already has depression and is recovering from anorexia, so I don't want anything too negative to get in her way!!

[user1483893543]

*Sticked up. Don't know were stacked came from lol

[britainteascones]

Take it to the police, the school and the parents of the child. Racism/Xenophobia like this is not acceptable and a serious crime. Almost 13 year olds should know better. Goodluck. Do not dismiss the seriousness of this issue.