What's your opinion?

Ok, I know this isn't something that would usually be posted on here, but I just need to hear some opinions. My younger sister is 7 years old in the second grade. When she was in the first grade, she began to get bullied. I don't know why. She's so so sweet and wants to be friends with everybody she meets. She's beautiful and funny and just wants to play with everyone. She came home crying one day and told my mother and I that Two girls who she thought were her friends took her into the bathroom and beat her down to the ground while she was crying and saying to stop and asking why. Later, a little boy was kicking her stomach and making her cry. We emailed her teacher, and all she did was tell them to say sorry. What do you guys think? Should there have been more action taken? This isn't all that has happened. She is constantly beat up on and bullied physically and verbally. I feel so heartbroken. I just want to help her.