Amazon.in — Failed to deliver the product in discounted price - 2 similar incidence happened with me

Address:

Bangalore, Karnataka

I got 50% discount of ordering Hush Puppies shoe during their so called Independence day sale. I paid the amount upfront using my CC on 10th Aug 2015 and after waiting 21 Days they couldn't deliver the item. Courier service didn't mentioned the real reason of delivery failure. When I was in the call with Amazon customer service representative was asking me repetitive times to cancel that order and replace with a new order. Finally they processed the refund on 31/08/2015. Same thing happened with me for another Lee Cooper Loafer shoe which I ordered 33% discounted price. Next day the price of the item went up and same night I got the order cancellation email mentioning item is out of stock. This time too I paid the amount upfront using my CC. I need some advice what step I can take against them since they accepted the payment hence do they not bound to deliver the item in agreed price??