Cognizant Technology Solutions — delay in release of offer letter from cognizant

Address: Hyderabad, Andhra Pradesh, 500032

I have attended the interview in Cognizant on 1 june. The HR ( MUTHUPALANIAPPAN.[protected]@cognizant.com) said in a couple of days he would send me the offer letter. But still there is no response at all. I have been mailing them but they dont care to reply at all.
It's been difficult to even contact and the consultancy (Concepts hr consultancy) is not at all responding properly.