Reliance Mart — Rate always higher than Offer shown

Address:

Reliance retail limited Sandhya tower puruliya road Ranchi Jharkhand

But bill when I saw that in almost every item more money was charged as compare to the offer displayed in the store .
After complaint they told that kindly return the amount they will provide credit note for which I have to purchase another product of same value .
They should refund the difference amount directly rather harrasment