express booking on airasia is cheaper than normal booking

[Jah_rastafar_I]

seems like if you have flown on a certain flight before lets say singapore to hk you can select express flight to get a cheaper rate. Just found out about this.

 

[Hanace]

seems like if you have flown on a certain flight before lets say singapore to hk you can select express flight to get a cheaper rate. Just found out about this.

Just checked express booking on Air Asia, price still as normal not cheaper. Maybe I missed something. How do you do it.