Armacell Process Engineer interview questions

They took phone interview first and then an online test. After this, called me for an onsite plant visit. After a week I got rejection saying that someone else got selected. 3 days later my rejection, I got a call from the HR saying that they want me for that role. They said they will process my letter and send it to me with a potential start date. 2 days from then they sent me a mail saying that the management will not be sponsoring so they have to take back the offer. "rollercoaster ride".... Such a bad administration. I have never been treated or misguided like this ever in my life. Thank god I was not selected. What if after I start, they ask me to leave since they did not know..