Flipkart - Refund from flipkart not received

I had cancelled the oreder for mobile phone and flipkart said the refund is already done from their side but there is no refund amount received in my bank account. Flipkart says its bank issue and gave me ** digit arn no. But bank says they dont recognize any arn no and
their system dont strack such numbers and asked to contact flipkart for these matter. No one is taking responsibility and I am feeling frustrated and helpless. Its flipkarts responsibility to look into the matter and solve it soon as the amount is big. They had sent me mail about the incident and only asking to contact bank and bank is saying they dont have anything to do with it.