end of the story (2 weeks left in Germany):
kind of advise for any shot-term visitor
go to Saturn shop
get O2 modem pack comes with O2 sim card for i-net
ask them to do registration for you
buy vouchers at their cashier
top up via modem or by your phone (easier option)
plug modem
enjoy
Everything else .... will cost you some time to sort out. Do not waste your time ... pay a bit extra for the service ...
Bye all, it was my pleasure
