I can't comment on blonde rai as never used it, but I would have bleach bathed (strength permitting) and then applied the desired colour.
Sounds like her hair was very porous and has grabbed the colour, I'd get her to leave it a week, and if hasn't faded enough then try lifting it, but you will have to do that for free given its not come out as planned.
I always insist on strand tests when it comes to things like this so you know how it goes x