BuildingMinds Senior javascript developer interview questions

Started great and ended horribly. It all went well till assignment round until I was given an assignment with 3 hours length although it was a week longer if you try to finish the whole task. I picked up a part of it and tried to complete it. Then came the review round where two tech team members joined and they started reviewing and I started explaining and there was a part where I couldn't explain well my approach as I put that just as a normal thing without thinking much and interviewers even though understood that I am not able to explain the part well, kept on emphasis only on the same to the point where it looked like they are making fun of my knowledge about the subject and they stretched for 1 and half hour just to show their own knowledge on that topic just to reject me on a mail afterwards.