Cognizant Technology Solutions — Offer letter not received

My Name is Vaishali .
I had my technical interview with Cognizant on 7th May. Post that HR called me on 11th May for my HR round. I had a discussion with her regarding Package and joining date. After some days one HR called me to fill the CIS form and I was told that I would receive the offer letter in next 2 days.
It’s been more than 2 weeks now but I haven’t received any updates from the HR.
I dropped a mail to her and even called her twice but no response.