New hair dresser+ fuck up??!

I had my hair partially highlighted a week ago.

I have naturally dark brown hair. I wanted light brown highlights. It looked good as I left. Then the next day in better light , my hair was 100% white!

I went back, she was horrified. She said she thinks my hair has high porosity and it didn’t take or it soaked the toner up.

As far as I know, she bleached and toned my hair.

So anyway she toned it for a longer time, added a developer with it, it was great after! Two days later, I’m seeing white streaks again.

Does she need to use permanent dye, is she making this up and she just fucked up my hair at some point with like the bleaching? She’s only been a stylist for a year and I’ve never had problems with this in the past.

Any hair dressers who can shed some light? I can’t keep going back. I need a real permanent fix here. Thanks