Logitech Product Manager interview questions

The interview lasted for 1 hour in the face to face round. After which i received a mail asking for payslips and refence checks. I musthave thought how come i came to the end of the hiring process? I was wrong. was told that i will get a call from US and i attended the phone interview, Then next day i was asked to attend two Face to Face interview with other panel members. Then one fine day i was called for HR interview. The one fine day i received a regret letter. That is it. I wondered why did they asked me the references and payslips in the first place without even completing the hiring process. The HR personnel was very amateur in his job.