Rolls-Royce interview questions

Video interview (pre recorded questions and answers), phone call with HR manager, and assessment center in Goodwood. Overall very positive experience on the day, thoroughly enjoyed the interview process and day in general, but follow up process was very unprofessional. I was told everyone would be contacted in the next 3 days as they did "not want to keep people waiting" to be informed if you were successful or not. I received a call the same day from the hiring manager saying they were very interested in me for the position, and even called me back for another interview for an additional job. After this I did not hear from them for 3 weeks, e-mails were ignored and I eventually had to ring HR myself to find out I was unsuccessful and was not given any feedback on my interview when asked. Other applicants received the same treatment. Very upset with the level of unprofessionalism in informing candidates, successful or not.