Hectic skin reaction / burnt

Not sure if anyone knows what is actually in the MK treatment (in-Salon), their website is very clear that it is natural products and no added chemicals or toxins (I did my research prior to doing the treatment). After I did this treatment, it caused such a bad skin reaction, my neck looked like it was burnt. I contacted MK who advised that there was a % of Formaldehyde in their treatment but have failed to advise what else. In my mind this is misleading information from their website : "free of harsh chemicals and toxins". The products also make me itch very badly and irritate my skin. Told to stop using them, however after spending close to R1400 on natural and toxin free hair products then to have to go and buy other products is not on! Terrible service from MK, have mailed them a few times and still not coming back to me. I am wanting to know the exact ingredients in the treatment to ascertain why it caused my skin to react the way it did and why it burnt my skin, however they are not replying with this info, which is questionable. Be very careful what you read or believe about this treatment and their products.