National Instruments Technical Writer interview questions

Incredibly unprofessional. After 3 rounds of HR nonsense interviews, two technical interviews, and one test assignment, which in total took up to 7+ hours, they couldn't even be bothered to send a rejection letter, or any sort of feedback. Even though, multiple times throughout the process I was told that I would not be left hanging, expect a response in 3 days, etc. I tried reaching out to multiple people, none replied, except for one HR person who just said that the recruiter is out of office. No return date or anything like that, and now it has been well over a month. Incredibly rude to have people go through your entire interview process then just ghost them. Especially when you are strongly implying during the interview that they will send an offer. They also kept setting up interviews while not really considering the 7 hour time zone difference. The company itself also didn't list out pay, benefits, and when asked, they pointed me to their career portal, which, again, had none of these listed out. I don't know if the blame is with the Hungarian office, or the US one.