don't worry, my first 2 weeks of school I had black hair and really really pink bangs. It was bad, lol. I bleached my hair a few days ago, now I have orange and pink. There's a rainbow going on up there XD I love bleaching pre-dyed hair, it leaves the hair tye-dyed.
The same thing happened to me when I trued to give myself blue tips T.T it turned green. There's only one color changing solution! MOAR DYE! that might also be a really bad idea. It'll work out somehow though! don't worry!