HAIR STYLISTS! I have a question for you =) ?

i used to have veryyy blonde hair last year, and went to a light to medium brown. yesterday i had my stepmom (shes a stylist) put some blonde foils in but she didnt do what i thought she would. i used to be dyed blonde with lighter highlights but now im brown with blonde streaks and i lok stupid. my stepmom is stubborn and i cant ask her to fix it... what can i do to lighten the brown? she put a gold toner on and said it would take care of the brown but it didnt. can i put like half a scoop of bleach in my shampoo and wash it? or should i just mix some bleach and developer?