For the thousandth time, there is no seniority in Qatar Airways. Seniority here is like this: 1) Locals, 2) Connected people (we have several mafias over here), 3) everybody else. I have seen people with clean records denied upgrades/fleet changed for no reasons whatsoever (or flimsy reasons a la reporting 5 minutes late more than a year prior) but some guy with a warning letter and a reputation upgrades because he is a local/knows the right people, etc.
Once again, this is a job for people with no other options. If you have a steady job at home or one that you like, DON'T LEAVE IT TO COME HERE. This notion has been well covered in the past.