How can I get feedback from an interview? (When I have not heard back)

I had a job interview for a full-time runner post recently and the interviewer ensured me that they would get back to me within a week to hear about whether I had been successful or not. I have since not heard anything and obviously have not gotten the job but I have sent subsequent emails to which I have had no reply. If anyone has any advice for me about this situation and possible ways to move forward that would be very much appreciated.