Employer not willing to relive as per employment terms and extended notice period

Dear Sir, I work for a world renowned medical hospital which is trust in Mumbai. On 26th of April I have submitted resignation letter which earlier they refused to even receive and inward department has been instructed not to receive. Somehow with follow up, they have acknowledged and given me a received copy. Upon a series of hated discussions, I have been insulted many times. On 22nd April, I have written a follow up letter they have refused to accept so I had sent it by speed post and scanned and sent over email. Today ie 23rd April, they responded that "you will be relieved from the services of the Hospital w.e.f. 27.5.2022, the last day of your work after the close of office hours, subject to completing necessary exit formalities". I responded that 1) My new company will not wait. 2) Appointment letter terms talk about 2 months. 3) This is unfair to have this communication just before 4 days to end of my notice period and further requested to relive as per original terms. Please guide me how should I get lawful exit and reliving letter with final settlement of payment