We don't have the same examination procedures as you do, and our qualifications are different (but equavilent, and not saying at all one is better or worse than the other) to yours.
Was this a semester test, or a final cumulitave exam?? A lot depends on the wheight of the test, as well as whether this test is a exit level test of not. Unlike with tests, when treating patients, you do not (often) get a second chance. Hence, should you be unsuccessful in any examination, you need to sit down with your lecturer and go over the test/exam, to see where you went wrong. It might not even be that you did not know the answer, but just that you did not know to answer the question, but the result remains the same. Time should be provided for you to get your ducks in a row and fix the problem, only then go for the re-exam.
At the instution where i studied, we knew from day (of three years) exactly what to do in order to pass. There were no grey areas, did you also know have this info (Test dates, Assigment dates, assesment dates, etc.,)?? If you did (And i think you have), it is not the lecturer fault that you failed and you cannot say it is unfair not to give you re-exam, right there and them, as you knew what was expected of you to pass. Don't forget that these exams have to be moderated, normally internal as well as external to ensure the examination process is fair and the results are true. This also takes time...
Try placing yourself in the examiners shoes, this may give you direction as to their chain of thought behind there decisions. During my study years, a candidate once failed a module/section. The ball was thrown back to the rest of the class, and they had to decide whether it was fair to re-exam the candidate or not. The answer was not as easy to come up with as we thought. We all worked hard and passed, he did not, yet he was a friend to some, and to others not) and fellow student and maybe deserved to pass. What would you, or your classmates have done??
Anyway, don't not give the lecturerers the pleasure of seeing you throw in the towl, as sometimes that can be their objective (Wrong though). Get back on the hoarse and show them that you have put in the effort and you are more than capable then passing!!!
Good luck...