HDFC Bank — Charged for zero balance salary a/c

Address: Lucknow, Uttar Pradesh, 226001

Website: www.hdfcbank.com

I joined a company . As a joining formality the company has opened my salary account in hdfc bank, it was a salary account and i was told that i don't need to maintain any balance in this account ( it's a zero balance account).
Due to some reasons after 9 month i left that company . Also, i called hdfc customer care to close this account, and they said that, they we'll take follow
. Up on this. I got no any massage regarding this charge from two year ..He hide me from this, no one told me regarding this..Nor any massage
After two year i got massage (-6431.40)
I don't understand why this charge for a zero balance account?
My number is [protected]
From this num you got my bank a/c number