Hard to advise without a picture, but i would try and fade the current colour as much as possible first. Then neutralise the warm tones with either blue or violet depending on the colour you achieve.
Or you can use a colour remover, but that will take you back to the bleached colour. Then use a much cooler toned semi over it. There was no need to go so much darker just to ensure it covered the blonde, that was just an excuse IMO. You can tone out yellow with a very dilute violet dye, but it won't make your hair darker (if the bleachy blonde was much lighter than the colour you want.)
If you can post a pic it would really help.