All depends upon the terms of your written agreement with the company, if there is any.
Otherwise, there are three options for you:
(1) Convince the company with the genuineness of your claim: Or
(2) Claim through court of law after serving a legal notice: OR
(3) Compromise with the company to accept lesser amount, as the company may like to pay.
LAST BUT NOT THE LEAST - Don't jump to start with your assignment without entering in to the terms of business formalities in writing to your own satisfaction under the guidance of some expert.