Hair help!

Bella
6 months ago I died my dark brown hair with directions semi permanent dye on lagoon blue. I left it on for four
hours because oh how dark my hair was and dyed it again two weeks later, leaving the dye in two hours. I had to dye my hair brown just before school as 6 weeks after dying on was still very much green and that worked for a while but 6 months later my hair is a muddy dark green/brown colour that's vile. Have any suggestions??