Dont think packed food is always fresh

Purchased Amul curd packet today from a nearby shop ,
Its expiry date is 11.01.20 , but its taste is like it is a month old , and a very foul smell is coming from it with color is also not regular white which shows its not fresh (clearly taste is showing).

Complained it to the shopkeeper and he told me that he will ask this to distributor .

How can this happen when date is clearly stamped on it and that too with such a reputed brand… This creates a big question on how safe are packed foods , even much before the expiry date product is already expired ..