Company Harrassing me for Notice period buyout.

I joined the company with a three-month notice period and was informed that I didn’t have a probation period. However, after 23 days, I realized that the company culture wasn’t a good fit for me, and I received another job offer, prompting me to resign. I requested an immediate release and asked for the notice period buyout to be waived. Initially, HR said this wasn’t possible. In the same email thread, I escalated the request to upper management three times and even offered to forgo the remaining 13 days of salary. During the discussion, one of the Leads responded that I could be released immediately since I didn’t have any dependencies, but they didn’t clarify whether it was with or without a buyout. The Lead then went on leave for two days, and I planned to confirm the details with him on Monday. However, on Monday, the company locked all my accounts, informed me via my personal email that I had been released on Friday, and is now demanding three months' salary for a relieving letter, threatening legal action if I don’t comply. I didn’t even complete one month with the company, and they never confirmed my last working day through official channels. I only received notification on Monday, through my personal email, that I had been released the previous Friday. This is an Indian company.