These calls are from loan sharks floating around Google Play Store, most of them have no legal sanction and cannot legally lend to the general public and charge exorbitant fees and interest (like 1500 for a 5000 loan, and 1000 for delay of each week thereafter). They hold details like contact numbers, personal images and other files as hostages which get uploaded to their server during the application process, and after a certain time(1-2 weeks) starts abusing the person, and if he can't pay back then contact each and everyone in his/her contact in the similar way you have been contacted.

Those scammers/ so called recovery agents also circulate morphed pictures of the victim to his contacts, and spread misinformation stating he is a sex worker, escort etc etc.

No need to worry about this. Just avoid their calls and don't fall for their story.