Unpaid last month salary.

I am kidney transplant patient. i have joined one company in Feb. -2023. at the time of joining i gave affidavit that i will not ask for money from company for any medical conditions may arise in my tenure. letter on after few months i resigned on 26th April 2023 from company after serving my 1 months notice period which was till 31st may 2023. After notice period there was a mutual oral consent between me & director of company that my salary will be revised to x amount and i continued for 2 months. Due to workload and stress my medical reports ware againts me, so i informed and presented the same to director . Doctor advised me to go for biopsy of kidney that what I told to the director that i will discontinue my job because of medically unfit. I informed him on 15th July, 2023 that after 31st July i will discontinue my job. He told if your reports are in favor you may continue, but i have to go for biopsy so i need to hospitalize for few days and need rest after kidney biopsy. I completed my all work in progress as suggested by management. I spent 3 days more till 03/08/2023 for final completion of my work. It has been almost 2 months till i have not received my salary. when i called management they said you have not served your two months notice period so, you will not get salary of last month you worked and one more months salary company has to recover from you but company is not doing so. 1. As there is no appointment latter after rejoining on mutual consent, can company ask me for such 2 months notice period ? 2. they have changed their notice period from 1 months to 2 months for all existing employees also without any written consent of employees , can they do so ? 3. As there is no appointment letter after rejoining on oral mutual consent, Am i eligible for my July - 2023 Salary ? we have biometric system in company where i can find my attendance as i have worked for July - 2023. I was working for account & HR department so, there are signatures on it of my approval of vouchers which again proves my presence in company. What should i do ?