To get relieving letter and experience letter

Dear All, I was worked in a company as a project manager and filed my resignation on last week of Jan 2020. As per my appointment order, I have to serve 90 days notice period. Due to some internal politics and continuous humiliation from one of the company's director, I forced myself to step out from the organization on 1st week of April - nearly served 75 + days of notice period by mailing them as a disputed separation option given in the appointment order. A.O says, in case of disputed separation, employer can hold all sorts of pending financial benefits and may get money for unserved notice period. I have waited for the call from HR for last 3 months, but recently I came to know that , they are alternatively extending my notice period end date as June last week , now as August last week. I mailed them last week by stating all this issue, they asked for a week time, but now HR told me that they haven't received any information from top management. What I have to do to get my relieving letter and experience letter?