spencers hypermarket - promised offer not provided and cheated

In spencers app,i found an offer in chocolates section which was only applicable for one of the particular flavors of Hersheys kisses milk chocolates-multipack of *, so i ordered two packets and in real i should get ** items, but they have given only *, when i called to spencers kurnool branch and asked, he told its just company's mistake in displaying wrong image and spencers is not responsible for it, and today he told its rectified in app, but my issue is, if it is a company's mistake who should held responsible, either customer or company? i felt very bad for just cheating and when it comes to their heads they just bluff its company mistake in placing wrong image, i need justice