Mitchell International Software Development Engineer NET Java Level 1 2 interview questions

I have applied through LinkedIn in June. after 15 days recruiter contacted me and schedule a phone interview with a senior software engineer. On a phone interview, the person mentioned in the mail was not availble. Instead of this, a junior software engineer had taken the interview and asked questions related to topics those were not mentioned in the mail. After this, a recruiter sent me take home coding challenge and scheduled 3 hours of an interview. The coding challenge was consist of developing Restful web services based on the requirements they had provided. It was very easy to develop using WCF service in .NET . Next, 3 hours of the interview was consist of 3 interview round on skype. First was with a team directory. He was only asking questions on unit testing and syntax of junit cases. He was expecting lot more from Software Engineer level position-1. The second round was with two software engineers. They had asked questions related to basics of OOP, java collections and sql. The third round was another two engineers. They went through the coding challenge I had submitted and discussed how to improve current code, why you have used WCF for building service etc. On the same day, they sent mail of rejection in the evening. Advice - Don't waste too much time on the coding challenge or anything to prepare. Interviewers are not prepared well and there is discrepancy between details recruiter provide and interviewer ask.