Randstad Call Center Representative interview questions

The most disrespectful, unprofessional experience I have ever experienced in the hiring process. I was scheduled to interview with Randstad at 11:15am. Got an email at 9:15 reminding me my interview was coming up in 2 hours. Showed up to the interview 10 minutes early and waited for 40 minutes to an empty office. Attempted to call the office several times and got no answer. Emailed the person interviewing me and got no answer until after I had left. That person claimed that roughly ONE HOUR before the interview she called me and left a voicemail cancelling the interview as the position had been filled, although I had no record of a missed call or voicemail. She said she would keep my information on file for future opportunities. I attempted to confirm my information (phone number especially) was correct in their system for said future opportunities so as to not "miss" and more calls/voicemails. Multiple follow-up emails all went unanswered. The most disrespectful, unprofessional experience I have ever experienced in the hiring process.