Infosys Senior Manager interview questions

I went through employee referral process. Initial HR round happened. Then I was called for a face-to-face interview in India Hyderabad location's Infosys campus. Interview was medium complex - covering technical, pre-sales, management, leadership all round by 3 senior members. After that I received HR call and designation and package were discussed after sending all requested documents, HR provided verbal confirmation too on both designation and package. Suddenly I received regret letter that offer cannot be processed without stating any reason. When I replied back to same email, one HR called and started talking in very rough tone stating that she cannot reveal the reason and no further emails/calls will be entertained. When I further escalated this through my referral channel, no action was taken. In short, this is very unprofessional and rude way to deal candidates, worst ever interview experience in my 16 years of IT career, whereas I could have been their asset for future as I was coming from a much large and reputed organisation.

initially the course was selected by HR manager to select candidates. Then it was a direct interview by HR and then followed by reporting manager and reviewer. offer letter was released at a later date.