Unpaid of remaining bonus from last organisation

Dear Experts, I was working with manufacturing company since March, 2016 as an admin executive. I had complied 1.6 years in that organisation and after serving notice period, I resigned from that organisation. I got my salary in my account but without bonus in it. As per my knowledge, every employer has to pay bonus to their employee whether they are working pr resigned and in my case the best part is that the company have mentioned the monthly and yearly bonus in my CTC structure. Ideally company should pay my bonus as i worked 1.6 years and have served my notice period. After the discussing with my HR, they told me that they will not gonna pay my remaining bonus of 8 months as they have not mentioned the same in HR Policy. As per my knowledge, there is no such HR Policy in that organisation. Company was deducting PF, ESIC and bonus from my monthly salary then why they are not paying my dues. Please do the needful and suggest something in my favor. Also let me know how do I claim for this in my previous organisation.