KATHREIN-Werke interview questions

The worst hiring experience I ever had. I went to an first interview where they ask questions about my academic life and some basic technical questions. After 1 week I got and offer but then past 1 month they told me I were supposed to go to another interview because I didn't fit in the other position anymore. I went to, not 1 interview but 2 interviews. And in the end they told me that I was not the person they were looking for. So, resumed, I went from a offer to none, after 3 interviews.