Quantum Design interview questions

I applied and never heard anything at all from them. But a few weeks later I found out they contacted my current employer (without my knowledge or consent) to ask about me. I have never in my career encountered such unprofessional and indiscrete behavior. It's not like I went through all the rounds of interviews and then agreed to have them check my references. They just...blew up my spot. Ridiculous. I actually have half a mind to sue because it further eroded relations with my current employer.

I applied through a recruitment agency, and was soon invited to a face to face interview which went really well, it was informal and I had two people interview me, the MD and a sales manager. I was then invited back to a second interview where I had the MD again, but the sales manager who was meant to interview me again was not there, and instead I had a different person who I'd never met before interview me without prior notice. He then asked me all of the questions I had already been asked in the first interview (I wasn't as prepared for these as in the first interview because I didn't think I would be asked the same questions twice). Then I gave a presentation, where I was stopped every 30 seconds so that they could bombard me with questions on what I had said, before carrying on. I was asked some physics based questions even though they knew my background was chemistry. Finally I was given a tour by the MD and we had a general chat for around 10 mins before I left. I came away feeling quite positive but I didn't get the role and I didn't receive any feedback. I asked for feedback through the agency but they didn't get any after asking for it so I contacted the interviewers directly and finally I received some detailed feedback which was very useful. In addition to this, I had traveled the whole length of the country for the interview and was not offered any expenses.