“Hausverwaltung” completely ghosting the residents

Hi all,

Never thought I'd have to post here. Been in Germany for about ten years, but this is a new low and I need advice.

Since the 1st of January, the Hausverwaltung for our apartment block in Franfurt/Main changed to Capera (https://capera-immobilien.de/), which according to Google reviews seems to be the worst landlord in Germany. Which I find to be true.

Since 04.01, half of our apartment block has no heating. The other half is having issues with water/plumbing. Now the fun part:

* The contact number Capera provided appears to be unavailable.

* The (other) contact number on their website is a "Please stay on the line" merry-go-round which I rode on for about forty minutes and gave up after leaving a message.

* The "Emergency number" is a voicemail box which might as well be a black hole.

* Emails are being completely ignored.

* Out of desperation, I've called an external Notfalldienst to see if the issue is perhaps in my apartment (wasn't aware it affected the entire building yet). A guy came and checked everything – no problems at my place, so apparently a pipe burst somewhere or the cellar pump is malfunctioning/should be vented. Guess what? Residents have no access to the pump. But later one of the neighbours mentioned there is water dripping from the ceiling in the basement, so I guess a burst pipe is plausible. Also, I had to pay 225Eur to the Notfalldienst – pretty sure I'm never going to see that money ever again.

* The actual owner of the building is one of those companies which don't seem to be doing anything other than existing. No contact information anywhere except legal address on company registry websites. So no chance of contacting them I guess.

I'm honestly at loss here. I'm not freezing (yet), since I've bought two heaters, but this is going to make my electricity bills skyrocket. And it's a snowball's chance in Hell that I'm going to get any sort of reimbursement from Capera (but I've already sent them the Notfalldienst bill per email). I'm angry AF at the entire situation, and feel completely powerless. Is there anything that can be done legally?

I'm also thinking of making the time next week and dropping by Capera's office in Neu Isenburg personally, but I'm not sure this is going to amount to much either, since it's unlikely they even have a customer reception there.

Sorry for the wall of text. Any advice would be appreciated.