problems with obb nightjet client contact

Hi all!! I’m very worry about my reservation from Wien to Amsterdam with obb nightjet:

We’re 2 adults + 2 children and we bokeed a couchette.

On monday I received a mail from obb nightjet informing that there’s a problem and we don’t have the couchette, the company propose to travel on seats o cancel the reservation.

I’ve called two times to the company and the persons who attended my by phone are sure that my reservation don’t have any problem, all is ok. I’ve asked them some mail saying that (all is correct and you have your couchette) but they say is not possible (I don’t understand why).

So, someone in the same situation now or in the past?

Someone knows what can I do? I already have the pdf ticket, so my intention is go to the train station.

Many thanks!