Kotak Mahindra Bank — Kotak mahindra bank debit card double charge

I used the kotak debit card in mumbai at merchant yuvati (Dadar) for a bill of ₹9000 dated 15th march 2017. On first attempt the card was declined and the transaction was completed on the second attempt. I checked the bank account statement that the money was paid twice. I approached the merchant for refund and they showed us and gave us the copy of the latest receipt of only ₹9000