Hello @Afra Aba,
welcome to our o2 Community 😀
Thank you for contacting us with your request. I've been happy to take a look at your contract.
Our security department have already informed you on May 31st via text message that these high charges for international calls from abroad have been incurred on your phone number.
You can find the charges for calls in World Zone 4 in our price list on page 5. Please note that incoming calls are also charged.
The charges have now been billed with your current invoice. If you would like to make a payment arrangement, you can contact us by phone on 089 787 979 456. Unfortunately, this is not possible here in the community.
Best regards
Giulia