I don't think time suggestions constitute rules - they are suggestions, and indications of the relative weight of the portions of the exam. These are the kinds of things you should notice at the beginning of the exam, at which time you can probably ask that the professor be contacted for clarification. I just have a really hard time seeing how this is particularly unfair, or problematic to the point that it should be challenged. Everyone had the same instructions and the same suggestions. If it is really such an issue, then I don't think it's unreasonable to presume that many other students were impacted similarly, so (assuming a forced curve)...it shouldn't actually significantly impact grades.I get that exams are high-stakes, particularly IN THIS ECONOMY, so I guess I can understand wanting to challenge it on the chance it helps, presuming anonymity is maintained. I just personally think it's whiny bull.
While you shouldn't panic, you should be realistic. This is not a problem regarding your perception of how you did or whether you had a quality answer for the last question, it is a problem of not completing the exam. Have you talked to other students did they finish it or make substantial headway? If the majority did, you're probably in a bad spot. Fact is you gave away close to 1/3 of the possible points on the exam and meaning your max total is around 66-70% (if your first two answers where perfect, if you got say only 90% of the possible points on the 1st 2 you are looking at a max of about 59%) where even students who only got half the points on the last Q will be shooting for a max of 84%.