Amazon India — account on hold and refund not received

Address:

Mumbai City, Maharashtra, 400004

Hey,

My name is karn jain. I ordered an oneplus 7 pro on 11th august, 2019 and paid the entire amount with my credit card. The amount got deducted from my card and the order was placed. Within 30 mins, my order gets cancelled from your end. And i get a message from amazon saying that your order has been cancelled and if you already paid your refund will be initiated. It's been 6 days and i haven't received my refund yet. I contacted the amazon support and they told me that my account is on hold. I have given all my details to them including the bank billing address.

My registered mobile number: [protected]

I am also getting mails regarding sending them a fax of the details like the end 2 digits of my credit card details. Help me out. What am i supposed to do.