Early Cancellation

I have tried cancelling my contract for a mobile phone number with o2 at the following link: https://info.o2online.de/kuendigung/?_gl=1*16s0a1p*_gcl_au*MjYxODEwOTM4LjE3NDE3MTAyNzg.

When I select the “Ausserordentlich” cancellation option, there is some technical problem and I am not able to submit the request. I have tried this on multiple occasions (A few times in February, and again mid March). I am still unable to submit the request. I am, however, able to do regular cancellation, but this means I have to pay for my contract until it expires in more than a year.

When I spoke to customer service they told me to send my request for early cancellation (including my abmeldung in the email) to the following address: impressum@cc.o2online.de

I have not received a response in nearly a month, and my o2 account says my contracts still won't expire for around 400 days. I am now turning to the community so they can provide assistance. Thank you for any help.