Triple-S Operations interview questions

I was contacted to set up an initial phone interview and was offered an onsite interview immediately. In my opinion, the onsite interview went really well, and the interviewers said they would be making a decision within a week. It has been months now since my onsite interview, and I still have not heard back from them. I paid my own way to commute to Houston to interview with this company, and they did not even bother to follow up with me to reject me. The interview went well, I spent my own time and money to interview, and I was not even worthy of a call back. This is highly unprofessional for me and has removed any personal desire for me to ever communicate with them again. That is why I never followed up personally.