DelphianLogic Technologies Associate Project Manager interview questions

Whole day process consisting of aptitude test, GD followed by 2 PI. Process took place from 10 am to 7 pm. At the end of the day I and other 4 candidates were selected. HR informed us that the offer letter would be given after 2 days. I started following up from the next week. After 3 weeks of follow up, I was told by the consultancy that they rejected my application with no reason mentioned. The consultancy told me that DelphianLogic HR will send me the official mail saying the reason. But I never received one. Treating a candidate this way is very unprofessional.