Amber Labs interview questions

Very Unclear how many stages, possibly three/four/five . I had my screening call going through skills and experiences Then, the second stage followed by a Technical Interview with Amber Labs Technical Engineer went through Experiences and questions around Git, Terraform, AWS which was quite successful. Third stage, I was then briefed and invited to another technical interview which was with the actual mother company who sub contracts Amber Labs (basically Amber Labs is just a recruiter then technical service provider ), Interview was relatively easy and again questions around project work involvement etc. I was left with a very positive impression and confirmed by the interviewer expect a response in the next couple of days. However, I did not receive any feedback at all and did NOT receive any response to my follow up email either totally ignored by Amber Labs hiring team. Quite disappointing , after putting in your time and afford to accommodate all their needs why? I felt it was a waste of time and Amber Labs handle this very unprofessionally, such a bad experience for me !