I beg your pardon for boring you all with my issue, but I want to share with you that after one week I haven't got any answer to my mails neither from the seller nor from Wacker. That has since the beginning been the worst part of this transaction: few and late answers from the seller, no answers from Wacker.
After this experience I will strongly suggest to anyone paying their internet purchases with some mean that allows to recover money independently from seller mood.
In my situation I'm claiming my money back from American Express purchase insurance, though that will cost me 50 euro fee.