Yes. It's called yield management, and sometimes it can frustrate us all beyond belief. While there may technically be seats in Y, there may not be any in the actual fare class. You're not simply looking for a Saver fare, you're looking for a Saver fare in the appropriate "letter" class.

The best advice is be persistent. Try calling, if no good, hang up and call again. If you have to wait until you get to DXB, then do exactly the same thing if the first agent won't help, find another one.

Good luck. Report back with an update.