HCL Technologies — I'm an Ex-Employee and they're not providing Experience Letter & Relieving Letter

Address:

Address HCL Technologies Ltd, Chennai-SEZ, SDB2 Sholinganallur 602/3

I did an internship at HCL. I need my Experience Letter and Relieving Letter for background verification.

I tried submitting joining letter & payslip but HCL background verification team is not accpeting. Also they're ignoring my request to provide contact info of the concerned department to get Experience Letter.

I contacted multiple times on Employee Helpdesk but they hung up on me.

I found out on internet about separation portal. When trying to login, OTP only comes sometimes and that too around 10-15 minute late and this OTP expires in 10 minutes so everytime if I get OTP so late then it says invalid otp while logging in.

Also approached via Twitter but no response.
Every Approach I'm taking results in unsatisfactory response due to their ignorance.