I've used the PPI Color Correcting Shampoo before and saw no difference with red tones diminishing. It's a dark blue color, so that's probably the reason it didn't work very well. A color conditioner with green based tones is what's needed to correct red tones.

On some other forums Aveda Black Malva Color Conditoner is highly recommended to resolve red tone issues for 1b hair, but caution using it is advised because leaving it on too long will sometimes leave green tones in the hair. Also, Back2Natural Dark Ash Brown is formulated with a green base to it so that will definitely help with the red tones. I've used Back2Natural for years now and love it. (It does tend to dry out system hair a little bit, so I always condition my system hair after using it.}

Personally, I'd get both products and experiment to see which one works best. Another thing to try is using some of both mixed together, or on top of each other, to get more or less of an effect that suits your needs.

What ever you decide, I'd start with leaving the product(s) on for a minimal amount of time, dry and check the color of a small section of the hair, and up the application time accordingly until you get the result you're looking for.