unusual and challenging situation
 

Hi guys, I am in an extremely unusual and challenging situation.

Facts:
My car has been vandalized while parked at the condo's underground parking: a nasty scratch running from the trunk to the bonnet, and 4 tires cut with a knife. Obviously it has been one of the neighbors and I'm even sure which, but no proofs.

Context:
We live in Germany, where there are strict laws for the privacy, making nearly impossible to install surveillance cameras in shared areas. So there are no cameras at the parking and the condo administration refuses installing them. The only possibility to have a camera somehow is a dashcam.

The problem:
The dashcam would have a parking mode and would record all the events around the car, possibly including the same neighbor smashing the windshield with a sledgehammer and steeling the camera itself, with the records in it. His goal is causing me losses so this scenario sounds more than credible. Uploading the camera picture to a cloud would allow to have still the records with his face, but there is almost no network connection of any sort in the underground parking and the camera would not be able to connect to a cloud.

Questions:
Do you know any dashcam/in-car surveillance cameras storing the picture on a remote storage (better if wirelessly)? That's the only workaround I can think of. The storage device could be placed in a different place inside the car, so the aggressor would not even suspect it, steeling the camera.
Second question - what can I do to have mobile network at the parking? Any network extender or amplifier?
And the last question is pretty much related to the first two: Is there any alarm system based on different principles, such as walkie-talkie or similar? I would like to have a car alarm which would let me know something is going on at the parking (keeping in mind all the network limitations described above). My flat is 6 floors above the parking, so about 20 meters away from the car. It doesn't seem to be such a huge distance for the radio frequencies, even with some concrete in between...

Any hints for these or any other workarounds would be highly appreciated.