Why would you have fitted it to multiple clients if it was all that bad? Surely there must have been a few more batches that looked like this before they didn't give you a refund? Sorry but I'm just so confused, as sway said you clearly changed your story and it just sounds to me like you're a bit pee'd off with the brand to be honest with you because they didn't get your money back, a lot of purple shampoo's contain sulphates and parabens, which can cause the hair to go dry and can cause damage to the keratin tip (this doesn't mean that it will happen every single time) as itd be down to multiple factors such as; how long it was left on for, how damp the hair was, how much shampoo they used, whether it was put on every inch of the hair etc. So no hair company would recommend the use of purple shampoo.
I get where your coming from, but there's having an opinion and then there's going out of your way to make a brand look bad. Clients are naughty as well, and in my opinion are sometimes guilty until proven otherwise, they could have used all the correct aftercare, but also could have been holding a curling wand on each section for a minute at a time, you never know. All they can do is assess what you've said and make a decision which I think is very fair.