I had a mishap when coloring my own brown hair too - I went too dark, used a "color remover", and it turned a brilliant shade of light orange! I had a job interview later that day and panicked, did not have $200 for "color correction" at the local salon, and decided to call the Clairol hotline to ask what shade to buy. Wow, was I surprised.
A very nice lady walked me through the process, suggested I not use their products (it would turn my overprocessed orange hair green) and suggested a specific shade from their competition's line. I was stunned she was so nice to help me out this way, tried it, and $10 and less than two hours later my hair was back to it's original natural-looking shade.
In your case your hair color change might be less dramatic but I found their help in selecting the right product and shade invaluable. PS - to this day I use Nice & Easy for the most natural results as other brands leave my hair brassy.