That has go to be the absolute worst. I would want to kill someone if I was ten minutes from the end of the test and everything was lost.
I also took the test within the last week, and I agree with you that the Q section was more difficult that the GMATprep. I was also taken aback when I got hit with an extremely easy question towards the end of the Q section. In the end, my score was within the range I was practicing, so I can only guess that the extremely hard and extremely easy questions were experimental.
I wonder if the testing algorythm takes into account the difficulty of experimental questions that it presents to you. For example, if someone gets hit with a bunch of time-consuming tough experimental questions, will the test slip in a few easy ones to balance out the time that you were forced to waste?
Again, I feel really bad for you that your test was cut off. That's a nightmare.