I was banned in wa. So here is the way I solved it. Maybe useful for others.

Recommendation:

you already got wu installed and the config file is still there.

Got you're account unbanned by wa support.
Install regular whatsapp and register your phone.
then quit the application (closing like any other android application)
download from openrepos aliendalvik-superuser by coderus
search via google for "passwordextractor apk smorra"
install the application.
run the application
grant root access
take the given password and enter it into wu config.

AND THEN UNINSTALL ANDROID WHATSAPP TO PREVENT TRYIN TO ACCESS WITH MULTIPLE CLIENTS

Maybe this helps somebody. For me the advantage was that the register process is made by offical wa (so no uncertainty like usin wart). Was afraid to get banned immedeately again.

ahoy