FNF settlement

I served 60 days notice period. On my last working day, when I asked for FNF, company said to clear the dues (clients payment used to come in my account). So i cleared the dues other than the amount which was equal to my FNF amount . I told them ,this amount could be deducted from my fnf so you will not have to pay me either and i have also settled your dues. But they are askinh for complete amt and saying you can receive your fnf amount (salary+leaves) only after 90 days. And the company had hidden my car too, saying when you will give the remaining amount only then you will get this. What should i do?