Cognizant — Not received offer letter from Cognizant HR Team

I had two round of Interview ( June 26th and July 3rd, 2021 ) and then HR congratulated me and asked me to fill candidate information sheet & few documents to shared on 7th July.
i got call from (9th July) HR discussed about the job designation, few personal details, salary and she promised me to get the offer letter within 2 days.
Till now no call, no mail nothing. its been 10 days and no mail's came, i tried to call her and sent mail but no reply.
Please help me to solve my issue.