Sorry you had a sub-par interview. It sounds like your interviewer was bitter about his children not getting admitted to Harvard and wasn’t fully up to speed on Harvard’s generous financial aid. FWIW: more than 60% of Harvard students receive some sort of FA – and many students, including my daughter, attended Harvard for LESS than the cost of their state school. It also seems as though he was dismissive of your rank, GPA and test scores. None of that should have happened.
You could call Harvard Admissions and explain the situation to an Admissions Officer. However, interviews are not arranged by the Admissions office; an applicant’s contact information is forwarded to the local alumni chapter and the alumni chapter assigns an interviewer. Admissions MIGHT contact your local alumni chapter and request you be given a second interview with another alumni member, but I don’t know the likelihood of that happening.
Your other option would be to google “Harvard Alumni Association Your Local Area” and explore their website. For example, when I googled “Harvard Alumni Association Southern California” there is a tab on the website for members to contact someone at the alumni association so they can volunteer to be an interviewer (http://hcsc.clubs.harvard.edu/article.html?aid=111). If you lived in Southern California, you could contact that individual and explain what happened in your interview. You’d have to tell the contact person the name of the person who interviewed you, and it could become awkward. So, you may want to save this option for after decisions come out so they can delete this person for future applicants.