Online Loan Scam Is Defaming My Father

My father recently became a victim of an online loan app scam. He applied for what appeared to be a private finance loan, but it turned out to be fraudulent.

After installing the app, the scammers appear to have gained access to his phone contacts. They are now calling people from his contact list, using abusive language, demanding money, and making false claims about loan recovery. They are also attempting to damage his reputation and pressure him into paying money through threats and harassment.

the calls and harassment are continuing, and many relatives and friends are receiving disturbing calls.

We have advised everyone to ignore these calls, but we would like to know:

What additional legal steps can we take in India?

Can the scammers be prosecuted for harassment, defamation, extortion, or unauthorized access to personal data?

Is there any way to force telecom providers or platforms to block these numbers more effectively?

Has anyone dealt with similar Chinese loan app scams, and what was the outcome?

Any guidance would be appreciated. Thank you.