Myntra.com — refund not received by the bank

I ordered puma red ferrari shoes on 4th april and cancelled my order on 5th april. I was told that i'll receive my refund within 7-15 days. But it has been more than that. I contacted myntra and they said they have already initiated the refund with the bank.. When contacted with the bank they say that they have not received the money. Myntra gave me this reference number 74766519095913559851710. But seems like it is of no use. What do i do?