Arm Embedded C++ Software Engineer interview questions

First step was a teams call about my experiences and the second step was an assignment. I have perfectly done the assignment and tested for the requirements. I've sent the assignment in 3 days and they did not answer for 3 weeks!! Afterwards when I asked, they said that I am not selected for further steps because of my assignment. I find this is irrespectful because I've covered all the requirements of the assignment in my answers.