ICICI Bank — Demat account still not deactivated

Address:

Hyderabad, Andhra Pradesh, 500084

Acc :[protected]
Last year march 2016, i went to icici bank hitech hyderabad, i submitted a request to close the demat account linked to mentioned account number. I was acknowledged by the staff that demat will be closed within 7 days. No receipt or any written communication or anyemail was sent to me as the confirmation of demat closure.
Today, again i received a yearly demat account charges of 800 rs.
ICICI BANK, please let me know why should i pay when i already requested to close my demat account?
If demat is not closed, then it is not my problem. This is something that is missed by your staff.
Please be informed, By any means, i am not going to pay this amount.