To correct color that is too orange, they will apply a blue-based toner. The blue will neutralize any orange you have in your hair and bring it back to a natural looking color.
They will have to do a color correction service, which means it will either be rinsed with a bleach hair stripping agent or just bleached. Then to remove the brassy color, toner will be applied.
They'll strip the color then redye it back to your original shade. Make sure to get a good conditioner to use because your hair will be weak after that.
