The company isn't accepting my employment permit and isn't giving joining after giving me offer lett

I am a Bangladeshi citizen staying in India on Long Term Visa(LTV) . While I was studying in India on Student visa i have been offerd job by an IT company named CAPGEMINI .I haveshowed my Bangladeshi passportand all the details during my technical interview for the company.After that they have given me LOI .Then I have been granted LTV by FRRO and ministry of Home Affairs. I have done my aadhar,pan ,bank account by the LTV . I have also done the preonboarding training under the company. After that they have given me offer letter and asked to fill a widget and enter all the details.i have entered the details. I have received offer letter too and I have taken employment permit from the FRRO for the company as its purely private in nature. After that the company starts behaving like they don't know about my nationality and they areassumning that I don't have valid work permit in India. but through LTV I have got work permit anywhere in India in purely private company,starts my business, andetc. So what legal steps can I take now?