Dear Vicky,
Your organization has already reduced the notice period to 45 days against 90, so you have to serve 45 days notice. This is your problem you you can not serve more than 30 days owing to some problem inherent by your wrong decision.
In this scenario the only way out for early reliving is to convince the HR for buy out the rest period or settle against amount due from F&F. In my suggestion you should complete the asked notice period, if your employer is not ready for buy out option. There is legal recourse but it is time consuming and not suitable for carrier growth.