I have coloured my hair 3 times today.  First time was lighter, all it did was lighten my roots and the rest of my hair stayed dark.  I covered it twice more with a darker colour but it hasnt stuck.  So I still have yellow roots and dark blonde hair.  Any suggestions?

Okay, don't dye your hair anymore today.    Give your scalp and hair a rest. 

What have you done to your hair in the past?  Is this yellow color that you have from bleaching to yellow with bleach? 

What you have is called HOT ROOTS.  The scalp is much warmer and will cause the reaction from the dye to process faster and also "lighten" the hair a bit more. 

What are you trying to accomplish?  All over dark blonde? 

Let me know what you want to do and I may have a suggestion.

Unfortunately I didn't see your reply....I coloured it again this morning.  This time with a L'Oreal Dark Blonde and it looks OK so far! 4 times in two days must be a record. 

I was trying to get my hair a mid ash blonde, I love the colour Mariah Carey has right now.  Your hair is grogeous but i just dont suit it that light.

I think this has toned down the roots some more which looked a bit orange in the end....

I have had my hair light, then dark, then light and so on.  The last time I had it coloured was at a salon and I had Diacolour (a long lasting semi permenant)

I think I am going to ban myself from purchasing any more har colour

For future reference, when your roots are the only problem, just dye the roots a darker color to match the ends.  I think this would work.  But I am glad you like the color you used.