Concrete in the pipes of controlled residential ventilation

Hello!
We have a huge problem right now.
Our installer laid the ventilation pipes for the [Kontrollierte-Wohnraumlüftung] a few weeks ago between the steel layers for the ground floor ceiling.
The next day, the concrete ceiling was poured with cast-in-place concrete.
Today the installer wanted to connect the pipes, etc., and noticed that concrete had gotten into two of the pipes.
Now the question is how this could have happened.
Could the pipes have been damaged by the concrete workers, or are they so sturdy that this is rather unlikely?
Otherwise, the only possibility would be that the pipe connections didn't hold and thus came loose.
Or do you have any idea how something like this could otherwise happen?
And above all, can someone tell me what can be done now to fix it?
Relaying the pipes in the screed?

It would be great if someone has experience with this and could give me a few tips.
So that we don’t look completely clueless at the appointment with the installer tomorrow. Of course, now probably everyone wants to shift the blame to avoid paying for the damage...

Phew, I doubt whether the pipes can be easily cleared like that again. However, I am not an expert.

What is definitely still possible: Lay flat ducts on the concrete ceiling (before the screed comes).

Purely out of interest: Could the ceiling be removed again and re-concreted?

You can definitely be able to do a lot. But it costs a) time and b) money.

However, whoever has to (or wants to) teach a or b is on a different page.

Who supervises the construction work (architect/site manager?) and who pays that person's salary? Without expertise, I wouldn't discuss with either one alone.

It is rather unlikely that the concrete worker damaged it... they must have come loose at the joints...

So, we have now found a compromise. Since 2 of the pipes are really completely full of concrete, a connection must have come loose somewhere. This could not have happened through any small damage to the pipe. Of course, no one can now determine who is to blame. Maybe the installer did not tighten the connections enough, or the concrete worker was so careless and rough that they came loose during the concrete installation. In any case, they will now share the work/costs. The concrete worker will make 2 core drillings through the ceiling. And the installer will then re-lay the two pipes on the concrete ceiling. I was really shocked at first, but now everything has still been resolved quickly and well.