HDFC Bank — Negative balance in the account

Address:

Chennai, Tamil Nadu

My salary account(In hdfc bank) was created in my first company. I resigned from my first company after two years. And its been almost three years now. And suddenly i thought of checking my hdfc account to resume and use it as my savings account. But i was shocked to see that it was already converted to savings account from salary account(Without any information to me) and that it has negative balance in it. And my balance in that account is now -6596.91.