Z-Ben Advisors interview questions

I was contacted by an HR who scheduled an initial phone interview. The interview was then rescheduled on the day of, because the interviewer was apparently sick. The interview was then rescheduled three more times, each time the HR contacted me (after the time we had agreed on) to say that they couldn't reach my phone, which was untrue because my line was working and I was able to receive other calls. I found the process very unprofessional - the HR would confirm a time with me before confirming the time with the interviewer and when they couldn't reach my phone they refused to attempt conducting the interview on WeChat or Skype. A total waste of time!