Giant Food Stores complaint: Double standard of showing Senior citizen card

I bought some fuji apples, roasted cashew n potato chips n paying at the cashier. So I tap my passion card to earn points n told the cashier that I am a senior citizen. The caahier insisted that I must show my senior citizen card to be entitle for the senior citizen discount of 3%. And then I show her my merdeka generation card n she told me its not this card. The merdeka card are issue to those born on 1959 n before so I must be over 60 years of age. But the supervisor Miss Jenny mending the other cashier told me that I must show the citizen card inorder to earn points. So I told her that I have been buying things from this Giant supermarket for more than 20 years n all the while other caahier only need me to tap my passion card on the reader n thats it. Why now must I show my senior citizen cardin order to earn points? I am confused? Please advice!!!