Consumer has the Right to be Informed about the aspects of goods and services that they purchase. These aspects include quality, quantity, potency, purity standard and price of goods.
If I buy a medicine and come to know that the date has expired, I will ask for replacement. Severe action can be taken in the case of defective medicines.
I would strongly protest this unethical and unfair business practice. Also, I can complain about it and ask for compensation from the shopkeeper.