Neighbours’ contractor damaged my bathroom ceiling

I had been away over a month, and during the time my neighbours above my unit started a whole bathroom renovation. They haven’t finished. I came back to my place and found there’s a crack on the bathroom ceiling, and some plasters and concrete pieces fell off on the shower booth.

I contacted the neighbours, and they said they will send their contractors tomorrow to inspect. I first thought the crack could be only on the surface, but now I’m afraid if the crack is deep and might get leaks from upstairs… and I’m also concerned if those contractors only offer cheap fixes. I may sound paranoid, but I have experienced bad ones before...

My question is, what could be the cause of this kind of crack? Could it be only on the surface, or a deep crack from upstairs floor? Of course it needs an inspection, but I want to be prepared and confront if the contractors are not willing to fix properly.

My building is from late 80s and ceiling/floors are concrete.

Thanks for the help