Merchant can deny chargeback if they can produce Proof of Delivery (POD) or they have already issued the refund. In your case as merchant claims to have refunded the money, please ask them for Refund Reference Number, share it with ICICI and ask the status of the refund. There are chances that since it is an International Transaction, it may be stuck requiring some compliance, which if you clear, the amount will get credited. Sometimes banks don't handle these international transactions properly. In either case I wish your problems get resolved and you get your money back.