HDFC Bank — Amb chrg incl st & cess charges in hdfc account

Address:

Bangalore, Karnataka, 560017

I'm a customer of HDFC bank. My account was a salary account earlier and later it was moved to a normal account. I have been using this account for the past 5 yrs. Recently amount of Rs.858.75 was deducted as AMB CHRG INCL ST & CESS charges. I was making sure that I have maintain average monthly balance in my account every month. Without my knowledge, this much amount was deducted and I'm not sure on what basis they calculated this charge and without informing the customer how they are deducting like this?. Pls help me in getting my money back from the bank, ...any procedure I have to follow to raise a formal complaint anywhere ? My account no. is [protected].