Ich habe die Lastschriftzahlung von O2 für die Prepaid-Daten nicht geschafft, da mein Konto in Deutschland nicht mehr existiert.

Hello @saaaa ,
welcome to our o2 community 😀
You can either get a Voucher (worth at least 20 EUR) from someone in Germany and get the corresponding code. 
Or you can top up by bank transfer:

• Send an SMS with the content "Bank" to the short code 56656 (free of charge) with your O2 prepaid mobile phone to which you want to transfer money.
• We will then immediately send you the O2 bank details and your personal reason for payment by SMS.
• Use these details to transfer your desired top-up amount (freely selectable). Make sure that you enter the correct reason for payment, otherwise you will be charged back.

We will inform you by SMS as soon as we have received the money and your prepaid credit account has been topped up.
Good to know: The personal purpose of use always remains the same for a call number. You can simply save this and the bank details for future top-ups.(→ Guthaben aufladen )

Kind Regards, Solveig