I need help with understanding how the DBS multiplier account works?

Hi, recently I called DBS to ask why my whole month of Feb don't have any interest earn. They said that cos its prevailing base interest & interest is calculated daily, despite retail paylah spending under Option 3, my interest earned daily is $0.000, thus month-end is $0.00. Can someone help me understand how Multiplier is different to normal saving acc, e.g. eEveryday saving acc? Cos DBS say if I hold $1k in the acc, month-end earn $0.28.