Shoprite Twin Palm - Change payment

I'm from this ShopRite branch and when the teller(female) was supposed to give me change, she only had coins. She gave me the coins so I thought to recount. I found that a 50n was missing. I expected her to tell me that she didn't have enough money but she just kept quiet. Wanting not to embarrass her, I just left the store. I'm highly dissatisfied with the service