I can't access Mein O2 on my main account

Hello, my main account name should be thomas.giannini1993, if not just send me a private message on this one.

Unfortunately I have lost my contract, therefore I don't have anymore my four digits pin.

Every time I try to login on my main account, it will tell me to write it to confirm my main phone number, and it won't let me do anything else until I provide it.

The page will still mark me as logged in, however I can't see my personal data, nor ask a question in the "hilfe" section, and if I click on any section of mein O2 I will be redirected to https://hilfe.o2online.de. All I can do is clicking on Login verwalten, but I can't complete the procedure.

Let me know if there is anything else that I should provide.

Best regards,

Thomas Giannini