Need help- Kidnapping case

Dear All, I have registered case under section 363,323,506r/w,149 ipc on 27-10-2017 it a kidnapping case & 20 members got involved. After 20 days 7 persons directly surrender to the court & took bail... Moreover remaining 17 persons not yet arrested investigation not happening.They manipulating the case with local corporator and local leaders. I approached to DCP & ACP on 9-11-2017 they instructed to CI & SI to file charger sheet & submit to the court ....but till date police didn't file charge sheet & they not updating case status & giving vague answers. How to get case status? How many days need to file charger sheet? What should be my next step? How to deal with police? Is there any RTI act office where I can get the reason for getting pending? Thanks in advance. Regards, Ali Akram