Leidos Software Developer interview questions

I was contacted by the hiring manager for a telephone interview. They missed the interview twice and they did reschedule it saying that the interviewer dialed the wrong number, although I was initially contacted on the same number! Then, I did the telephone interview; I was asked about my experience and the interviewer described the role and the recruitment process. At the end of the call the interviewer told me that the next stage will be a technical assessment task to do and return back to them, which means I passed the initial telephone interview screening. I have waited couple of days and they didn't send anything. I contacted HR and then they came back to me with a regret letter! They didn't show any respect for their applicants! missing the interview time twice and then saying something and doing something else!