Ok gusy, need some help here.  I have a customer who I am having a problem keeping a VR color in her hair.  I use Matrix socolor 3VR & 3N with 10 vol. all over the head.  It turns out beautiful but doesn't hold for more than a week.  She is using Biologe color care shampoo and conditioner and her hair is in decent condition.  Any suggestions on how to keep the VR in her hair?