[Jacqued]

Sadly it's a very common behavior. I have seen companies who will blacklist your phone number once they ruled you out. So you have a number, call them, interview, and after the interview when you try to call again to get an answer, you are asked to leave a message which will never see a response. In the meantime, someone else who has not been interviewed yet will call that number and reach the interviewer.

I can get past people not calling me back to say "no" but i find this kind of behavior quite despicable, surely taking 30 seconds to call someone must not be such a hassle (after all, you've already spent at least an hour interviewing them).

TLDR : get used to it, and just ignore them like they ignore you and don't apply there again