Not serving notice period

I have resigned from my organization on 08th October and informed them in my resignation that my last working day will be 22nd October and also ask them to nominate someone so I can hand over all the details before leaving the organization. As per my appointment letter, it is mentioned, "It is mandatory to serve notice of 15 days for termination of services during the period of probation on either side. Upon confirmation, the said notice period on either side will be one month. The option of offsetting, partly or fully, the notice pay by way of payment in lieu of notice period or by adjusting the privilege leave at your credit, it at the discretion of the management. In the event of exercising the provision of payment, in lieu of notice pay shall mean the gross monthly salary / gross salary for 15 days for employees under probation and one month for confirmed employees, including any other allowances payable." My resignation has been accepted by management but they are forcing me to serve 30 days notice. due to some circumferences, I can not serve for 30 days. please suggest what to do?