"German rights" does not contain a refund in any way. You can only get a refund if you can fully return the article you got, but this is simply not possible with a download (it's the same as when you buy a music cd: You can't get your money back once you've opened and used it). The files of the game are still on your computer, even if your account is "locked".
Have a look at our terms of use and eula, both are available in German.
We cannot give refunds for Steam versions ourselves by the way, we have no influence on that.
You should rather tell us the errors, then we can help you about it.
Please watch your language for your further posts.