Jorn,

Can you explain to me how Back2Natural Blonde would neutralise brassy tones from blonde hair and restore the original colour by depositing shades of black?

You've stated: "B2B colors your system darker with shades of black " as a fact.
Its not a fact I can find repeated anywhere or by anyone else, so I'm wondering where you've gotten this fact from?

Why would you have to bleach a system to remove it when its a temporary colourant that washes out?

Its the worldwide leading brand for this type of product.
I can appreciate you were unable to get it to work for you, but if that was everyone's experience, why would thousands people continue to use it?