Help i had my hair dyed and the colour is all wrong!?

okay, so today i had my hair dyed to a nice looking whitish blonde. it looked good in the salon, but when i got home, i noticed under neath the top that looks good, my hair looks white with a blue/purple silverish tinge. How do i get ridd of this!? When i tye my hair up i look like an old grandma because it looks slightly grey also. Please help!