HDFC Bank — negative balance

Address:

Near SBI branch, shilphata khopoli,Tal.khalapur,Dist.Raigad, Maharashtra,410203, Raigad, Maharashtra

My salary account (In hdfc bank) was created in my first company, so once i left the company and joined somewhere else i had to open another salary account. Now my salary account in hdfc bank has been converted to savings account (Without informing me or warning me) in the month of sept i received a call from customer care and raised a request to close my account as i did not want to use the account and they did say that they will follow up with the request and close the account. After that i never logged in to my account through net banking. I logged into my account for some reason on 20 apr 2019 and i see that i have rs -3500 in my account. I request you to please take action against this bank.. Thay have no right what so ever to do whatever they want without informing the customer. As per new rbi guideline bank has no officials to charge the customer any pending charges. And i visited the bank branch in khopoli. I have requested them to close my account. They have tell me (Angrily) u should have to pay the charges otherwise the account should be go to minus. Plz help me about this.