While it’s no excuse, I think most of us have lost our rag at some point after endless frustration and not getting any answers. Trouble is, it’s often directed at someone who is totally innocent but is in the front line so has to take the flak for someone else who is the real culprit.
Years of experience has taught me the best way to get something out of somebody is to be totally non-threatening, smile as you greet them and say something innocuous like “couldn’t they find the key to door then” and laugh. This will often be reciprocated.
Later in the flight, perhaps as you go to the bathroom, you can then quietly ask the CSD what really happened. 99 times out a 100 you’ll get a response. It may not be the truth but you won’t know that but at least you’ll be satisfied.