Notice Period buy out

I have resigned from my company on December 1st, 2021 and my notice period is 2 months I have stated I need an early relieving by 24th December and the max I can extend is till 31st December due to personal issues and for next 30 days I will buy out my notice period by paying my basic salary in lieu as per the offer letter terms (You may quit the services of the Company at any time with due notice or in lieu of salary thereof, just as the company may conclude its employment relationship with you at any time without assigning any reasons with due notice or salary in lieu thereof. For the purposes of the notice period only base salary would be considered in both cases, employee as well as employer). i am also ready to give the KT in case someone replaces me before 31st Dec 2021 else I can do the KT to someone internally. But now my management is saying that notice period buy out is as per management discretion which is not mentioned in the above clause and i will have to wait till they hire someone and even they are being abusive and shouting in the office at me that they will not relieve me until there is a replacement. Please advise what can be done in this case.