Hotel Wald in Warsaw

We booked a hotel through Booking, arrived, checked in, wanted to pay by card, the man replied that the terminal does not work only in cash, but you can pay later, we went into the room, renovation since the 80s. My wife found mold on the windowsill, the child is allergic, I made a cancellation on Booking and we went down with our things, to which the manager pounced on us and did not let us out of the hotel until we paid 350 zlotys for going into the room for 10 minutes, I said that I do not have cash, to which he replied that you can pay by card, and the terminal is already working, I said that I will not pay and he began to threaten with the police, I took my wife and child and we left there. In general, I was left under a very bad impression of this hotel, and the management who evade taxes, I think that they need to be taught a lesson for such actions