Flight from Hanoi, Da Nang to HCM City still remain

Actually, the so-called shortage of air tickets to Ho Chi Minh City could only happen for the flights at the peak hours, however seats are still available for passengers on other fights the same days.
Specifically, there are still around 800, 2,800 and 1,300 unoccupied seats from Hanoi to Ho Chi Minh City for three days of 7,8,9 February, and 200, 1,000 and 800 seats from Da Nang to Ho Chi Minh City.