Signify Senior Automation Engineer interview questions

Initially HR told, there will be 3 rounds of interview but later on they have taken 4 rounds of interview. Manager is incompetent, she was no able to decide whether candidate fit for the position or not. Finally HR sent mail that congratulations you are selected but never released an offer. When i contact her then she told, we have already finalized candidate . If anyone back out then we will give offer to you. Highly unprofessional and unethical. I think people should think twice before joining this company.