ZF Group Data Scientist interview questions

I completed the whole interview process and was offered a job which I accepted. I then waited 1 month without receiving a final written offer letter or contract. Two weeks before the proposed start date I emailed HR to express my concerns that the start date was coming up and I still hadn't received a contract. I had to relocate so I requested to delay the start date so I would have time to move after receiving the contract. HR ignored me until a few days before my start date then told me that they decided to cancel my offer because of the request to delay the start date. Be careful if you're relocating. They have the most incompetent and uncommunicative HR team I have ever dealt with.