Cognizant — regarding delay in date of joining

I am selected through off campus drive in february 2019 and received offer letter in the month of march. I didn't receive any date of joining till now. I have been waiting since 7 months. Cognizant made us to sit at home without work (Date of joining/any pay). I kindly request to either give date of joining or end a mail that their is no oppotunity..