HDFC Bank — Bank account

Address:

Lucknow, Uttar Pradesh, 226010

I have an account previously it was salary account later bank converted it into the savings account and since last one year i am not using the account, now i logged in and saw that the balance is -5000. according to RBi policy bank should not let customer's account balance go negative, according to RBI bank should inform customers about this and limit the services related to the bank account but balance can not go in negative. I did not get any sms or email regarding this.