I recently flew with Qatar Airways from Singapore to Europe.
I booked online and tried to rebook since my plans changed.
This was almost impossible. I got varying, conflicting advice. I was told to rebook via e-mail since I booked online. It took weeks to get an answer to my request and was told to rebook by phone. By that time the price to rebook doubled and it was cheaper to buy a separate one-way ticket.
There was absolutely no help, support or advice by Qatar Airways.