Flipkart - Refund not credited to my bank account

I have ordered flo ergo mattress in flipkart on **th August ****..by *th September they cancelled order stating that product is out of stock..i claimed for refund..they said the money will be credited to your debited bank account on or before **th September..i didn't receive any refund to my account..i raised an issue regarding this in flipkart, again they asked me to wait for three days..at the *rd day when i asked about the refund they answered me that they already refunded my money you can contact your bank.. when i contact the bank they said they didn't recieve any money to account..again i asked in flipkart they said i will get a mail in that reply with my bank statement for their verification..but till now I didn't get a mail from flipkart.. whenever i speak with customer care they always ask me to wait for three or four days..