Hello @Phan_Nguyen,

thank you for your request in our community!

As you are not registered here with your telephone number, unfortunately I cannot make the change for you. Therefore, I ask you to write a private message to our user @o2_Support  with your request and the corresponding phone number as well as your 4-digit personal customer password. For sending a private message you need to go to the profile @o2_Support and click on the button “Privatnachricht” to start a private conversation. Then we can have a look.

Thank you and have a nice weekend ahead.

Jessica