Exosite interview questions

Heard back for a phone interview about a week after applying to the job. The phone interview went well and after another week they offered me an in person interview. The interviewers were 20 minutes late and I was put in a room by myself forced to just twiddle my thumbs for that time. Once in the interview they seemed uninterested and as though they had other places to be. I understand it was just an intern position, but my time is important as well. I followed up with thank yous, did everything right and didn't hear back. Finally, after two weeks they emailed to say they wanted to offer me the position. I accepted and was excited. A week later, I again hadn't heard about a start date, time or any of the logistics. I called the hiring manager and the original HR contact atleast five times with no answer. Another week passed and they sent me a short email saying they no longer wanted to hire me. Rude and unprofessional.