Note that the entry new service is only possible if the GSM modem is connected.
In the zenOn directory you will find the executable "SrvSetup.exe". Please run that file. After startup you have to browse the germanservices.inf-file (same as you do in zenOn). This inf.file is stored in the zenOn directory too, so it should already be visible in the browse-window.
Please follow the instructions to add the services you need. The program will exit automatically, and after that you will have the services available in the message control configuration.