Your natural hair has more ash tones and the system is fading and becoming brassy in tone.

You should use a sun protector on your system hair, but you can restore the original colour and remove the brassy tones by using Aufero Colour Conditioner.
You would need a Mid or Dark Ash Brown.
Its very simple to use. You just comb it in and rinse it out.

Its available here:
http://r.ebay.com/gbUlv6

and there is more information here:
http://www.facebook.com/Aufero