Cognizant — waiting for call letter more than 11 months

Address: Chennai, Tamil Nadu

I got selected in cts in march 2017 throught campus in chennai and got my offer letter in july 2017. But still now i didn't get my date of joining. When can i except my doj. My friends from other college got there's doj in feb itself, then why there is delay in my doj. I'm waiting for more than 11months sir. When can i except my date of joining. Please help me sir...