Xiaomi India — money not refunded after unsuccessful delivery!

Address:	Kolkata, West Bengal, 700039
Website:	mobile.mi.com/in

I had ordered mi a2 with exchange offer on 24th oct. Exchange failed due to minor scratch in the phone and they refused to develer the phone to me although i was offering the exchange value in cash. They said they will refund in 7-10working days. But today is 14th november, still didnt get the money. And in the app it says refund successful!! Help!