Hello @Zubair.Ahm and welcome to our o2 community :-)

Changing your bank details works over our web portal and our Mein o2 app. On our web portal just select “Meine Daten” on the left hand side after logging in and then klick on “Ändern” on the right hand side at the “Zahlungsdaten” area :-)

I hope i was able to shed some light on this issue, if you have still open questions feel free to ask, we will answer as soon as possible :-)

Regards,

Lars