Help, i need to lighten my hair, cheap.?

i died my hair dark brown, but left it on too long, now its black, i let it grow for about 5 months and then put a blonde on it, my roots are ginger and my black hasnt shifted. i then used colour b4, with sent it an auburn colour, i tried putting a dark blonde on it, and it went ginger roots and black again:/ im now stuck with blonde roots and black hair, but the thing is, my natural roots are coming through, luckily no one can see them, yet! i want my hair ash blond for september, what should i do, i dont want to strip my hair, and i want to do it quick and cheap, as im 15 and dont have a job yet, any answers?X