Construction halt because the wall collapsed? When to continue building?

Hello, I am new here in the forum. Thanks if someone feels like saying something about my problem!

I have received a building permit (BG) to renovate, cellar, and extend a small (40 m2), over 50-year-old holiday home in the outskirts. According to the BG, two and a half walls were supposed to remain, whereby in the third (half) wall a central chimney stack was allowed to be demolished, and large window openings were approved on the right and left. In other words: Wall 3 was only supposed to survive in fragments. Hence "half" wall.

Now, during the demolition of the old building, these fragments of wall 3 or the "half wall" crumbled away. The masonry was brittle. However, two walls stand perfectly. The building authority then ordered an immediate stop to construction and declared the BG "illegal," since nothing from the old house remains now, this is no longer a renovation, but a new building, which they would never have approved.

I am now left without the old house and with considerable costs for cellaring and underpinning the walls. The building authority just shrugs, saying that this is my problem and that I have violated the conditions.

How can I continue building quickly?

PS: Brandenburg!

Specialist lawyer

Expensive. But okay, if it helps. Funny thing is: I was only threatened with a “forced payment” of 800€. So I could actually continue building and possibly pay that?

Clear. After the fine, however, other enforcement measures can still be applied. Detention, for example. Is that funny?

A fine is different from a penalty.

Sounds plausible. But wouldn’t there have to be another letter saying "if you don’t stop now, we will threaten coercive detention"? Or do they just show up at the door? The point is: my basement was supposed to get its cover on Monday. The slabs are lying around now... But probably that just leaves scorched earth at the building authority?