Cognizant — Pending in offer letter

Address:

Hyderabad, Telangana

I was selected in interview process held on 2nd July.
On 12th July i got hr call that I got selected in technical interview and done with managerial round and need to submit further documents for HR discussion.
I send with required details.
Same day I got hr call on 16th July with confirmation of joining, salary discussion and designation.
I was given surety to get my offer letter in 2 days ...but it's been 5 days no update i got.
I tried to contact hr person but his number and mailed to him but no response.
Please resolve this ASAP.
I'm really hoping for positive response.