[Resolved]  HDFC Bank — changed my salary account to saving and afterwards imposing non maintenance amount.

Address: New Delhi, Delhi, 110059

Hi, i have salary account in hdfc 2 years back when i was working at that time. After that i changed company & they provided other bank account. Recently i changed new company. The new company have using only hdfc salary accounts. But my hdfc exsisted old salary account showing -8500 balance.
The bank converts my salary account converted into savings account & charged monthly.. Now its 8500 negative balance. Without my permission how can the bank convert my salary account into savings account? Even they are not intimated verbally... According to rbi guidlines on savings account banks not charge even its negative balance.
I approach branch, but they behaved rudly & refuse to close account.
Plz juistice to me. 8500 is huge amount to me. What is the solution?
What is the action will take against this bank.