Send more mails to them, if they still refuse to answer get regged in their official forums (if you aren't). If that does not help write what has happened on some big sites (surely you have some real geeky site in germany too) that often helps alot.
About the open-box-"law" it is the same here in sweden, the only chance to get a new one is if the CD was broken when the game was purchased. Sometimes not even that will be enough for them, as they claim that you have broken it yourself...
