Stupid Exam Question!!!!

Today I'm having my thermodynamic paper and thinking that I am able to do very well. First two questions are easy and I continue with essay part. As I read the question, I know that the question contains errors because the lecturer took the question directly from text book. But he did modify the question in order to make the question more complicated. At the end, the answer turned out to be unlogical at all. When I asked him regarding this, he said my answer was wrong and I tried to recheck my answer but I didnt find any mistake in my calculation steps. So i asked him again and he still insisted that my answer was wrong. I started worry because I didnt want to miss any marks in this paper. So, I proceed with next question. The same thing happens again and now he left out one important info for us to do the calculation. I asked him why there is a missing value in the question and he asked me to read the question again and he tried to walk away. But this time I was smart because I asked him to read the question himself and soon he realised that he forget to put the missing value. He went to his office and almost last 5 minutes of the examination, he shown up and told us the missing value. He didnt extend the examination period and everyone was rushing to do the calculation. I had wasted my time in asking him and cant finish my last calculation. The chance of obtaining A for this subject looks very slim.