Full and final settlement not done by company

I was working in company that's was a pvt limited company. After the 8 year of my job and over burdon of role and responsibility even I am not capable for this responsibility . I have decided to join another company and give resignation and accepted the same and I have served the notice of 18 days instead of 45 days notice. First department hod not want releive me on 15 days notice but after suddenly he was agree to releiv. A new commer joined few days before as a manager takes hand over with me. I am surprise that I am only a executive and my handover to a manager level employee. But it is ok , thats not my problem . Than after the handover I got my releiving letter and departmental clearance document . Now I am asking from hr through email and phone also but they did not reply on mails but on phone and whatsup they are saying it will be done soon. My salary, earned leave, gratuity is pending with them . Now hr says your HOD says , he did not complete his work.