I'm so sorry to hear this.
It sounds like she knew what you were talking about but did her own thing anyway.
I certainly would have discussed the cost with her since she didn't do as you asked. $50 to ruin your hair?!
I don't have any suggestions on the yuck removal, other than a good strongish (sulfate) shampoo. And then maybe a nice relaxing DT.
Hopefully you can let your hair grow out a bit and then get those layers blended in better.