You can also load money to your Amazon wallet via Uber app using your Credit Card and also get your credit card rewards/cashback.
By default credit card loading is disabled.
Monthly limit is now 10k for bank transfer and 20k for merchant UPI payment (total 30k monthly limit).
For merchant UPI payment - open your amazon account on any other device or login any other Amazon account, now pay your credit card repayment, manually enter your Amazon wallet UPI ID and accept from your Amazon account.
Ta-da! now you paid credit card bill using credit card.