Hmm, you got a pic, or an explanation of how they messed up? Sometimes just combing/gelling it the right way can pull of the look, or perhaps you need to cut it again (even shorter, sadly) in order to even it out. Good luck if you're going for the bald look next!:-/
If you wear urban clothing, get a hoodie, throw the hood over your head and its all good. If it 's too warm where you live right now, cut the sleeves off to give it a rugged/tough look.
If you dress formally, unfortunately, I have no suggestions for you.
Go to a diff barber maybe, let them correct it, or go back and tell this person you want a refund or get it corrected for free