Bad service during my DSL activation .

O2 charges the fees for the Umzug to provide a perfect service . If the TAE is loose or not this is of course not my problem this is the problem from the Techniker . Unacceptable to pay 50€ for this kind of service. Of course I am waiting for an answer from O2 side ! 

If you do not want to push the TAE back into the wall yourself, call customer services and request a new appointment. If you want to complain about the Telekom technician, send in a letter of complaint.

In the apartment is provided flush-mounted box, that's why the hole in the wall. The flush-mounted box must be installed by the owner, matching the rest of the switch / box series in the apartment. There should actually be a double frame for power socket and TAE socket. However, as already mentioned, the flush-mounted socket is the responsibility of the owner.
The telecom technician only has surface-mounted TAE boxes with him. Of course, the technician could have screwed the surface-mounted box to the wall, but the hole in the wall for the flush-mounted box would still remain. 

I therefore assume that the technician has recognized that a proper looking solution can only be done by the owner and has therefore refrained from drilling 2 additional holes in the wall as a temporary solution. The 2 holes would have remained visible even after the installation of the flush-mounted box, which would not have been a good idea.

The telecommunication cables do not pose a risk of electric shock, as the cables are insulated and the stripped parts of the cable are inaccessible in the TAE socket.
With DSL connections, however, there is practically no measurable voltage on the lines any more anyway.