Worried about first semi-perm color

Hello. Please, could someone help me? 4 weeks ago I went to a salon for a cut. I have baby fine hair, natural ash blonde with lighter pieces from the sun. It's texture is shiny. The stylist said I would look "fabulous" with a darker warm brown semi-permanent color. She showed me a medium brown swatch of hair with "copper" highlights. She was really nice and said I would look so much better. She said it would wash out to my natural color in a month or so anyway so there was no risk. But now my hair is all one muddy brown color and my highlights and shiny texture are gone. My friends asked me why I did that to my hair.I called the stylist to ask if I could wash it out quicker. She said it would never completely come out even though it is semi-permanent because my natural highlights were more porous. But at the salon, before coloring, she had told me the brown would fade out completely and there would be no risk to my natural color.Please, can anyone help me understand what happened to my hair? Can anything be done to get it back besides waiting 2 years? Thank you to all who make this board possible.