Regeneron Research Associate interview questions

I was contacted by 2 different HRs for 2 different positions. A month after applying, both of these HRs just randomly called me out of the blue and conducted a 15-minute interview without any prior notice. They never scheduled a call or even emailed me before the phone interview. The application at Regeneron clearly asks for a person's immigration status so the HRs were clearly aware (or at least they must be) about my status. During the interview, they asked me about my visa status again and I told them that I will be needing sponsorship in the future. One of the HRs told me she thinks I'm a good fit and would be getting back to me but NEVER DID. I was even contacted directly by a hiring manager at Regeneron who said that she and 3 other scientists wanted to interview me but the HR would not let them because of my need for a visa sponsorship! The second HR called me about this other position that I had applied to, (again without prior notice), scheduled my interview with a hiring manager. I asked her about my visa sponsorship, she told me she would get back to me by the end of the day but I never received an email from her about the sponsorship or confirming my interview. The following week, I did receive a call from the hiring manager, who conducted my 30-minute technical phone screen. At the end of the call, I requested her to send me her details (at least an email id) or the HR's details. She told me she would, but I NEVER received any email from her either. It was very disappointing for me since I was rejoiced to receive a call from this company knowing its contributions to the field. But this behavior certainly let me down. And what's SHOCKING is that in spite of being contacted by 2 HRs and a hiring manager, and having these rounds of interviews, I never received emails from these people nor do I have a proof of my interviews with them. I think this is VERY UNPROFESSIONAL and I'm not sure if I am ever going to be that excited to apply or work for Regeneron!! P.S.- If you're an immigrant and applying for an entry level position at Regeneron, I would strongly advise you to stay away from WASTING your time and effort in completing that tedious application! There are a lot of smaller companies out there who would value and respect you as an individual and professional!