hair help!!

I dyed my hair a vibrant sapphire color about 2 weeks ago to finally realize I hate it. So 2 days ago I bought professional hair dye in the color blonde and tried to dye my hair back. The sapphire ended up not going away and just showed through! Then I decided to try brown the next day and the same thing happened! I really need to get rid of this ugly sapphire hair color before October 7th! Is there any advice anyone can give or something someone has done to get rid of this? Please help!!!!