EKART FLIPKART - Fraud case

We received a message from Ekart on Wednesday during office hours that there is a COD order of Rs.***. When the delivery person called me after sometime, I asked him from where the order is and he said from shopify or something. As the delivery person was genuine whom we know since we are regular customers so we didn't doubt anything and made the payment. Initially he shared a QR code against which we made a payment of Rs.***/-. Then the delivery person called me again and said that he by mistake sent the QR code of another order by someone else and requested me to pay the remaining Rs.***/- to his number so that he can adjust it in their system later on. In the evening after reaching home and collected the item from the security guard. After opening we found a cheap quality toy car which we never ordered in the very first place. I called back the same delivery person and asked him about the seller details as no seller details was mentioned on the box. He shared me his in-charge's contact details whom I requested to share the seller details by checking in their system. But he simply mentioned that there is no way he can track back the details of the seller. I mentioned him that if in case I didn't received the item in the very first place then they must have return the item back to the seller as per standard procedure which simply indicate that they do have the backward linkage provision in their system. But he simply denied providing any help. So, I want my full refund and file a case against this foul play by this reputed delivery partner.