Amazon India — order saying it might be lost

I made a pre paid order of 'nancy drew stroy book series' through amazon app on 23rd august. It had to be delivered by 3 september but wasn't delivered by then and the delivery date was changed to 7 september but it hasn't been delivered till now.. On the app, order status is saying 'dispatched and your package might be lost'.. I tried contacting customer care by phone and through amazon app customer service chat but of no use. I'm very furious about it.. It was meant to be a gift for my little sister for raksha bandhan but on the contrary it hasn't even reached there.. Quick action must be taken to either deliver my order or make a refund before i move to customer court..