On notice period for resigning

Hi , I have shifted jobs and use to work for a real estate firm , wherin the contract of employment was that i would be on probation for a period of 6 months during which my notice period would be 1 month and on confirmation it states notice would be 3 months , i have received no letter of confimation and have completed nearly 22 months of service , during this period i have not received my salaries on time , inact i receive it around the 20th to 25th of the month , and m ncentives etc have neevr been paid since my joining , i found another job and gave one month notice as i received no cofirmation nor underwent any appraisal in the 22 months of woring , i resigned by giving one month notice after discussing with the director, howver on my last workign day i was told that i need to serve 3 months notice and my resignation has not been acepted , im in a dilema now as this clause in the emloyment contract can be used against an emolyee i his srvices are not required and could be used for when requird . Please let me know how to approach this .