Who should I talk to about my high DLS invoice amount?

Hi,

Phone or livechat are possible ways (not all speake english), but in my opinion it is the best way you write a letter with youre questions, includs youre adress, custem-number, copys of documents and on top the word "Rechnungswiderspruch", and sent it to o2 by post or fax

Telefonica GmbH

Überseering 33

22297 Hamburg

or fax 01805-880088

Remeber that you can sent fax from youre PC with a programm like PDF24.

Greetz