Paytm Mall - Empty box delivered

Sir I ordered Boat earphones *** for ***/- on **th February ****. Order Id is **********. In Amazon and Flipkart, its price difference is ***₹. So, l ordered. Product delivered by Blue dart. My father received the package. After I came and opened the parcel I saw the box little bit tampered. I thought it's ok, shipped from Mumbai so some damage has occurred. I also found that the weight was less. Although earphones are not heavily weighted. After opening the box I found that it's empty. Then I called and messaged many times but they told that they can't initiate refund as the package was delivered to me perfectly. I am frustrated with the response by the customer care representative. They have to be supportive of the customers in spite of judging them while complaining.
Its irritating me how they cheat their customers just for Rs. ***. They are fraud and thieves. I feel happy for one thing that I have not ordered high price product otherwise I will become mentally harassed as their service is worst no one here to give correct information. They only say that "sorry for the inconvenience". Please help me. It's just not a matter of ***₹. But I want paytm Mall should know its fault.