Handshake interview questions

I applied for this role at the beginning of September 2020 with a well written cover letter and my CV. I have a decent amount of experience in customer support in the area of IT and databases. I was contacted by Handshake in the 3rd week of September and asked to complete a detailed mini project consisting of three support scenarios which needed access to their application. I spent a lot of time and effort researching and completing this. I submitted this in a few days. At the end of the month I was contacted by the Head of Handshake UK for an interview. The interview was more like an informal chat, I spoke about what I’ve been doing and I tailored my answer towards the role. I was told that there were 3 people short listed to go to the next stage at this time. I would be contacted to be interviewed with somebody else. Then there would be a final interview with other employees. The interviewer was friendly. The following day I sent the interviewer a thank you email and also expressed my interest in going to the next stage. However, I never heard back despite being promised another interview. A week has passed. I am extremely disappointed and upset at this. Why offer somebody any kind of hope during an interview? Surely the interviewer could have said he would get back to me later if I’m through to the next stage. This is incredibly unfair and unprofessional as I’ve spent so much time and effort preparing for the interview and completing the exercise. This experience has been incredibly demoralising. My experience in the last 6 months is that unless you apply for a role through a reputable recruiter you’ll get nowhere. Applying for jobs through online job sites has been a waste of time.