KAYAK Property Relations Manager interview questions

5 interviews in total 2 with HR department and 3 with senior management. I was told on email "congrats you got the job" then they call me to discuss salary and start date. I asked for extra 5% during the offer offer discussion, they answered no I confirmed I still want the position. 10 days later they emailed me and said although I have great skills and experience the manager has selected another candidate. HR team is the US looks very unreliable, unprofessional. I asked for feedbacks, no answer. The whole process to 4 months. No respect for candidates.