HDFC Bank — Account closure

Am not able to close my existing hdfc bank account. I visited the Nerul West branch of sector 6 for account closure. The front desk lady told me that I have my credit card linked to my account so not able to close it. So after few dYs with the help of customer care I successfully de linked my credit card. I even the same confirmation from customer carre. But despite this the Nerul branch lady told me that the card is still linked and not able to close the account. When she spoke with the credit card department of hdfc bank they both started arguing and finally that front desk lady told. Me to mail a letter with my own expense to the chennai credit card department. Am I joke to you guys hdfc? Stop playing and please close my account asap