Cognizant — Waiting to get offer letter

I was selected in interview process held on 25th Jun.
On same day i got hr email that I got selected in technical interview and need to submit further documents for HR discussion.
I have sent with required details.
On 29th I got hr call on with confirmation of joining, salary discussion and designation.
I was given surety to get my offer letter ...
And asked me to update with live picture on 30th june and i did it on same day as she shared a link that works for 30mins only after that i have called to inform her but her phone was switched off or not reachedable so I emailed and acknowledged for the same. On july 1st i got a call again from her and she said your live picture was not updated i have informed about the thing and she said she will get back with the solution but till now no update i got.
I tried to contact hr person but her number is switched off/ not reachaable. I have Emailed her but no reply from her end
Please resolve this ASAP.
I'm really hoping for positive response.