Blue Yonder Senior Software Engineer interview questions

I went through a consultancy. There were two rounds. one technical round which included coding and logical reasoning and one managerial round. The interviewers were interactive and the process went smooth and they were testing practical knowledge

They have conducted 4 rounds of interview. 3 technical and 1 managerial. Then collected pay slips and never released offer letter. Don't have minimum courtesy to inform. Worst experience and recruiter doesn't pick up calls as well. If they don't want to hire why are they wasting time.