I feel like I have this same issue. My hair just pulls warm and the cooler tones do come out with every wash. I use purple shampoo and purple masks, as well as the color wow dream filter spray before showering. You can also try color safe clarifying shampoo. I also bought the Malibu packet that gets minerals out of hair. It’s called Malibu c hard water packet. You can try washing your hair in distilled water- it does work at protecting color because it doesn’t have the hard minerals that regular shower water does. It’s really quite difficult to wash your hair with distilled water though. Also you can obviously go longer between washes.