color fix

I sent some colour to my mum so she could dye her hair during "lockdown" and it went very warm, she used well half 88/0 half 99/0 with 6% she has resistant grey hair that's why I used double base.the result was about an 8/04 not the outcome we didn't want, Im not sure what to put on to take...

Hello, any suggestions on how I can color correct this? I want to use Olaplex #1 in Joico Vero K-Pak Creme lightener with the lowest amount of developer possible. I'm thinking it would be best to bleach the yellow section first, and then the roots separately. Not sure what volume I should use...