Cognizant Technology Solutions — No communication from HR and delay in providing revised offer letter

Address:

Kolkata

I am 9 years experienced SAP consultant and has been hired by CTS on 22nd June 2022 with DOJ 19th Sep, but as I have resigned 2 days later from my existing employer, my LWD coming to 21st Sep. Hence, I have asked my recruiter via mail( no contact number shared) on 24th June itself to revise my offer letter in order to postpone the DOJ to any day later than 21st Sept. And now, today it is 16th Sep and without any single response from the recruiter even after following up 100 of times. This is least expected from an IT giant like Cognizant, their HR's should at least know the etiquettes to reply to someone's mail who is in dire need of a job with better salary. Please check if you can do
anything to resolve this issue. 10884990 is my Candidate ID.