Non-payment of EMI and intimidating phone calls every day

Sir I had taken a personal loan of 85,000 from an NBFC at 37% flat rate. I was working as a clerk in a Charitable Trust. I was paying the EMI at 5134/ 27th every month until the pandemic and the subsequent lock down came and eventually I being laid off by the Trust and losing the job. After the moratorium ending in August, their recovering agents began making calls every day, I mean every day and continuing till date with different numbers and different agents calling me intermittently and harassing me and threatening me of civil suit, CIBIL score and i had to pay at the court in Hyderabad in person. I asked for a waiver of loans for another six months so that I can collect the money and close the loan and a reduction in interest. They say they have no option for that. What should I do; 1. Can they call me and harass me every day. 2. Can an NBFC charge 37% of interest for a personal loan. Do they have RBI permission. 3. Can I file a suit for mental harassment and a waiver of loan?