Illumina Research Associate interview questions

TLDR; was invited to an onsite interview that was never scheduled. jumped through hoops to contact HR who claimed they "forgot" to reply to me and that the position was filled. Was invited for a phone screen with HR 2 months after I submitted my application. Took and passed the first screen and was invited to a phone call with the hiring manager soon after. I completed the second phone call and a few days later I was notified I passed. I was asked to provide my availability for an on-site interview over the next two weeks. I replied promptly. Two weeks went by without any reply. I followed up with an email to the HR; no reply. I called and asked to be forwarded to the HR rep I spoke to and was asked to email a candidate service email. I finally received an email from the HR person that was my contact. Was notified that the position had been filled and that he/she "forgot" to let me know. Very unprofessional.