Is it okay to ask for a refund if I am not satisfied with the correction?

I've had braces for over 3 years and it's almost the end, but the asymmetry and other issues that were supposed to get better haven't improved...
 In the beginning, they confidently said it would get better no matter what, and during the braces, I asked them several times because I was anxious, if it was really going to get fixed. They told me not to worry, but the results are so minimal that it makes 3 years seem meaningless, so I want to complain, but if they ask for a refund, is that real? Of course they won't give it to me, but I want to get a refund, even if it's just a little bit. F*ck, even if I wanted to get
 something like double jaw surgery now, they said my gums would be so weak because of the braces that my teeth could fall out. I'm so pissed off that I can't live like this.