HDFC Bank — showing negative balance

Address:

Gurgaon, Haryana, 122001

My salary account (In hdfc bank) was created in my first company, so once i left the company and did not use the account for 1.5 year now my salary account in hdfc bank has been converted to savings account (Without informing me or warning me) or even they gave me any letter on intimation or approach me regarding this and now i received a message from hdfc regarding balance check and when i checked the balance it showing -8000

According to new rbi guidelines banks are not supposed to penalise for dormant accounts but when i contacted the customer care they are refraining from closing it saying i have to fill the fine.
Where should i approach now. Please help cause i am not able to pay the fine