Company neither paying me my incentive nor relieving me.

I am working in a Pvt Ltd Company. I have signed a contract for two years from 1st Jan 2016 to 31st Dec 2016. As per agreement I should get Salary every month and Incentive every Quarter. It is also clearly defined that incentives muat be credited along with next months salary once quarter is finished. Now what they did is have not credited complete Amount saying we have hold your incentive due to a reason. (Which is baseless and no clause have been mentioned in contract) So what I did is I have emailed them from my official email ID and keeping my personal email ID in cc. Where I have stated "Clear My dues ASAP and if company is unable to pay me then provide me my Full And Final, Releaving, experience letter, Assets Handover letter" its been 20 days still they have neither credited my incentive nor provided my letters or incetive" I am not going office. On their request I have handed over everything. However I still have few assets of company with me. So please guide mw what should I do now?