Maha
"to the best of my knowledge it has not happened".
Well, Maha, we have just had three different people who are/were cabin crew for QR telling us it did/does happen. I find it a bit rich for other QR staff to come along and say it doesn't happen. Say "it is not a safety issue because...." or "we are short of staff so it is not a long-term thing" or "so what, our staff are so good they can handle it" etc. Don't just deny it.
You can understand staff, fearful of reprisals, coming to forums like this to air their concerns. QR have made no secret of their "if you don't like it, leave" attitude.
The current staff probably do like most aspects of their job, but are probably powerless to change the things they don't like.
Others are bagging QR out of bitterness. We are not stupid, we can see that for ourselves. That does not mean their gripes are not legitimate, or did not happen.
Denying problems doesn't make them go away. Try addressing the causes.