Cognizant Technology Solutions — Delay in receiving offer

I had attended Technical Interview on 24th September and received a mail that I have cleared Interview on the next day. I shared the Candidate Information Sheet along with the required documents. After one week, on 1st October I received a call from HR department and as per the discussion I was supposed to get the offer letter within a week. It's been a month now, still I have not received the offer letter.
CID is 18106262