Native Instruments Senior Market Research Analyst interview questions

1st round with the hiring manager via video call which was very good. 2nd round they asked me to do a research proposal which I learned later that I don't have to present it. I have a feeling that they just run the interview to get the research proposal for free. During the onsite, I had 3 sessions of interviews with 3 groups of people from 10 am to 1 pm without any lunch. Basically, I have to repeat my self-introduction and experience 3 times. It was completely a waste of time. The company promised to get back within a week and then after more than 2 weeks, they sent an email said they would go ahead with other candidates. I regret that I put so much effort into the proposal and for nothing! I feel being used by this company. And I have a feeling that they don't know what they are looking for! Not to mention, the company has no phone number that works. When you send them an email, it is up to them to reply to you whenever they want. I found this very unprofessional. The only good thing is they offered me accommodation since I am from far away.