Check if your used Airtel wallet previously. If it is in dormant, just leave it and create new wallet account from new number and done mini kyc. Then go to Amazon, you can pay the credit card bill from there. While payment choose Airtel NetBanking, Then enter your mobile number and MPIN, then click add and pay. There you will see credit or debit cards, Enter your card details and pay.
Maximum amount 9K per month. Do not open Airtel Savings Account. It is only for wallet users.