Big Bazaar — refund value replacement policy

Assuming a case that because of some reason a customer wishes to replace or get refund for any product immedietly after its billing. In this case big bazaar applies a policy which is against human rights.
In this case big bazaar should issue a voucher to the customer which he/she can use anytime or give anybody else with a life time validiity but instead of this it issues a voucher with only 15 days of validity.
In case because of any reason if the customer missed out to get any product with in those 15 days by redeeming that voucher after which the customer is not liable to get anything and looses all of his/her money without getting anything in return and all the money loosed by the customer goes into the pocket of big bazaar without any reason or valid point behind it.
While replacing an unused product, it is social and above that a legal responsibility of the seller in a retail market to give any product to customer of the same value which the customer has already spent. And as the money never gets expire or looses its value with time it should be refunded to the customer in form of the desired product. There should not be any time vaildity in such cases.