I am also facing same problem. Hopefully someone will see and fix the issue.

I also get the same problem and it’s not clear how to contact customer service 

Hello everyone,

thank you for your contributions to our community!
If something is adjusted in My o2, there may be a downtime. Generally, however, this is quickly remedied. Have you been able to log in again since then?

Kind regards
Jessica

Hi Jessica,

I’ve never been able to log into the myo2 app or view my contract details/ o2 priority options on the website since joining o2 (which was around a year ago). 
 

Hello @Rainbow_1916,

but you have aleady registered yourself with your number?
Click here to start the registration: https://login.o2online.de/idm/#/registrieren/start

Kind regards
Jessica

Hi Jessica,

I can’t access my o2 contract on the website, so don’t have access to the number attached to the SIM card in my router and as a result, can’t register.
 

Dear @Rainbow_1916 ,

did you register your Homespotnumber this way?
 

If not, please try to register your phone number again.

Kind regards,

Andrea