Indigo Airlines - Refund not received

I have booked etickets of Indigo flight through Amazon. After flight booking done I downloaded the Indigo App and there I booked my preferred seats and paid Rs **** through my own debit card, no agency or agent was involved in booking the seats. Afterthat I wanted to change my seats and Indigo was telling that they had refunded my Rs **** paid by me for seat booking. I have told many time to Indigo that I have not received the refund, but they are telling me continuously that they have refunded the money to the agency make my trip. But I have booked the seats by myself and paid Rs **** through my own debit card, then why I will not get the refund to my bank directly?? Why Indigo is telling that they have refunded my Rs **** to agency? Why Indigo is doing fraud with me? I have all the bank details that the amount Rs **** was debited from my bank account towards Indigo airlines directly, no agency was there, so I should get my Rs **** from Indigo Airlines directly, not by any agency. Kindly help me.