Mars Reward Manager interview questions

Initial conversation casual interview with hiring manager and was selected for Final Stage Assessment Centre - had to prepare a presentation and answer questions on it and then had a technical interview. Was told I would hear back the following week, after 2 weeks I chased the internal recruiter for feedback and heard nothing. After 3 weeks the online Workday portal showed I had not been selected. No feedback, not even an automated Workday email to inform me. I think if you’ve got to final stage interview the least they could do is to tell you you’ve not got the job! Very disappointed in the way I’ve been treated.