Non receipt of original certificate & dues

Dear Sir, I seek your help, I am aged 53 years, joined in a reputed educational instution as a Asst Purchase Manager, on July 2017, As i am not happy with system where i found lot of harassment by the other team members, I have submitted myresignation of march 2017, due to the assignments given were a merely clerical work to me, which is not at all related to my position, and which was kept pending by themanagement, As one of the other senior person from the management who is not comfortable with my work asked me to submittmy resignation,which i have forwarded the same resignation letter to the management,thru email which was accepcted by them and got the mail communication from the COO of the mgmnt and i am relieved on 6th April 2017. It was now going to be 45 days days, I am not received my original degree certificate as well as my salary PF dues for the period. I am keep on sending them mail, which i am receiving only evasive replies onlyby the pro . The HR team is not at all responding even though my mail was copied to the other members of the management. I am having the acknowledgement for the certificate which was retained by the mgmnt as well as I am having the copies of the email of my resignation. I am 53 now, getting another employment anywhere else that to without a degree certificate is highly impossible, also this is causes me a lot of mental harassment torture and pain. Please enlighten me, to whom should i have to approch for the remedy,and what should i do, to receive my original certificate as well as my salary and pf dues. Thanking you Kind regards., _____________ RameshBabu. Bangalore.