Positive Thinking Company .NET Software Engineer interview questions

I was contacted by representative via email offering a job in Frankfurt, Germany. I went through with hiring process and ended up with following numbers: - was interviewed by 5 people from this company (recruitment agent, HR, software architect and manager) - had various meetings with them on multiple occasions (about 10 meetings in total) - it took month and a half (from interview to interview) or about 8-10 hours in total. In the end they told me that they will get back to me in month or so with what they can offer me (they were acuiring some company and doing merges thus month long period), as now it is only matter of agreement between us. As I was waiting I declined a few offers coming my way, made a lot of research for relocation etc. After two (2) months have passed, I am thinking "maybe I should let them now I am still waiting for their response", so I send them mail. They responded to me broadly that we won't be continuing hiring process because of my German language skills. I was baffled by amount of disrespect and unprofessionalism by this company. If I haven't contacted them, I would never get response which they promised. Even though they never ever mentioned a word about me not having German language skills in these 2+ hour long interviews before, or anything else about what they think I lack. They took 10 hours of my life, promised a lot of stuff, destroyed a bunch of opportunities etc. This is the worst experience in my professional career so far.