HDFC Bank — closure of account

Address:

New Delhi, Delhi, 110018

I have applied for closure of account on 20-november-2017. I have done all the formalities for account closure, the bank executive told me to withdrawl all the amount in my account as he confirms me that account will be closed in next 15 working days and I have receipt for the same signed by one of bank executive which specifies that account will be closed in next 15 working days but still my account has not been closed and i get messages for non maintainance charges. I am always writing or contacting customer care but I never get any solution from past 6 months.