Sec 354D, 506, 509 of ipc and 67 A of IT Act

My friend is CA, who shifted to bangalore in 2014 for studies. One girl from andhra had training with him in bangalore for just 15 days. Then she went back and started sharing her personal problems with him. After 2 years One day she said her parents are not supporting her in studies because she run away from home and asked him to arrange a residence in chennai. Which was not possible for him. So he tried to discuss it with her sister to help her. But when that girl came to know that he discussed it with her sister, she got angry and filled false complaint of blackmailing on my friend. Daily he started getting calls from unknkwn numbers to report to andhra otherwise they are sending police to his home. At this point my friend got so tensed, somehow he found email of her dad and tried to inform the situation to her dad. But strangly he never tried to contact him. My friend went in police in 2017 but they did not even accept the complaint.. My friend got so nevers and depressed, he used bitch word for girl on messages.. based on those messages her dad filled complaint and my frined got arrested and put into jail for 15 days without arrest warrent. Also police registered fir in sec 506 and 509, but they changed those sections to 354D because my friend did not paid money asked by police.