My parents wont let me do my hair!?

They wont let me cut my hair! Its not like I want it short or dyed. I just want some bangs! And not even blunt ones, like sideways. But they say that if I get bangs I'll regret it. And that I want to change too much, and all I want to do is my hair. I want to express myself and they wont let me. And I'm not a bad kid, I have strait A's in school! I have tried asking them calmly but they always say no and get mad. I'm 13 and it took like a year just to get my phone. Help? Its really bugging me that they want me to be someone I don't want to.