Hair color remover??

I was wondering if anyone could tell me the best product to use to remove permanant hair color from my hair. I bleached it, then used a permanant color from sally beauty supply. I used a 30 creme developer with both. The color is cool(strawberry blonde color), but I was wanting to go to more of an ash blonde now....The woman at sally suggested just re-bleaching for a few minutes and said that should remove the permanant hair color, I tried it on a strand, and after 45 minutes with a 40 developer NOTHING happened! (next time I am using semi!) I would really appreciate any advice as to what product I can use to remove the color...I really don't want to spend $100. at a salon if I don't have to!THANKS!!Athena