United Bank Of India [UBI] — I am complaining about refund from Amazon

I am Jyoti Prakash Mishra, a customer o[censored]nited Bank of India . I had booked a ticket for railway on 26jan but it is cancelled and refund issued .But the amount doesn't credited in my account .when I contact the customer service they told me refund already issued on 31st Jan and they provide me a reference number 276658 and told me to contact bank customer service. They did not respond me. When I called again to Amazon customer service they told me to fill charge Dispute from .