I have had a color correction done with PM hair color and it went very well. The stylist took my crispy, light blonde hair back to it's mahogany brown and relaxed it as well, with no ill effects. In fact, I thought she was going to cut most of my color-damaged, natural APL hair off, but she managed to save most of the length, only cutting to just below my collarbone. My hair has been shiny and healthy ever since, and that was just over three years ago. Good luck with your color!
I had it professionally done. I had colored at home for years with no issue, but when I decided to go light blonde with my natural hair, I went to a salon that supposedly specialized in natural hair, and they proceeded to destroy it with straight bleach. I was scared to try to fix it at home, so I babied my hair for about six months rocking a funky but crispy two-toned afro until I went to another salon that exclusively used PM products. Been there ever since, and my hair is much happier for it.