The airline has a "Termination Department" along with the usual commercial, operations, sales etc
People jump ship whilst on trips, they simply leave their uniform in their hotel room and disappear.
Cabin crew have a curfew and must be back in their accommodation by 10.00pm, the building has a camera monitoring this.
Also cabin crew are encouraged to spy on flight crew and report any transgressions. A pilot used a first class seat for his rest period instead of business class, he was made to pay the difference between the two airfares.
Flirting between pilots and air hostesses is grounds for dismissal.
I have worked with a few ex QATAR staff and they all say it is actually worse than the stories circulating.