Zelis Dot NET Developer interview questions

I attended interview in zelis, they conducted four rounds(2- technical,1-manager,1-hr), HR said to me ,he will share the mail for document verification but I didn't received any mail , I called him and message him but there is no response from him. It seems they want to showcase their company not for hiring . Even after clearing all the rounds they will not send offer letter, Don't attend the interview in this company, it's waste of our time.