ANA Design Studio interview questions

The interview was pleasant. What happened later was highly unprofessional! I was interviewed and asked to complete a Revit test. 2 or 3 days later the boss called and said I was selected and even gave a joining date. He said he would send the offer letter soon. After this discussion, I gave my resignation in my (then) current office. And the same evening after resigning, when I called this boss, he was not attending my calls. So I messaged him to enquire about the offer letter. He replied that they were not hiring me because they had found someone else at a lower remuneration!! This is just wrong! Employers NEED to understand that people who are applying for jobs need to be respected and not be treated like trash!