Arbor Networks Software Developer interview questions

Met at a campus recruiting event, talked for awhile and was offered an interview. Interviewers were very intelligent, asked great questions, and had good conversations. I was extended an offer with a quoted hourly rate AND an on-site contact, however a month or two after the official offer they retracted and said they no longer had the spots available. Extremely unprofessional, especially due to the fact that I turned down another offer from a large company. They never sent official documents, however I assumed they were serious as the email instructed me to watch out for my onboarding paperwork in a week or so. Developers were awesome, the HR component was disheartening.