ZS Associates Knowledge Services Associate interview questions

My interview went well but due to some referals provided by our dean , i wasn't able to make it. There was a case study round and it went pretty well but i was getting 2 calls from ZS at the same time due to which i had to stop my interview which cused a disruption. i don't know why i couldn't get through

There were four rounds: an aptitude test, a versant, a case study round, and a personal interview with top management. The case study round was quite difficult, but they lacked professionalism in conducting the whole process.