I have encountered a few questions which were marked wrong, but still passed so had no need to appeal. I've heard of people appealing, it costs money to have the exam re-marked, it doesn't guarantee a pass though. At 45% I highly doubt that you managed to get that many questions which had incorrect answers as I doubt there are more than a small handful, if any.
The trick with CASA exams is RTFQ (Read The F*&%ing Question) and spending time to decipher the question and make sure you know what it is actually asking, quite often you'll find a question that is SIMILAR to a question that you have encountered in your practice exams, but there may be a keyword which makes the true answer completely different.
You may be able to pass some exams by rote learning answers, but you're only really cheating yourself.
Nathan Higgins had a very good technique he suggested for his Systems class. If you go through a practice exam, be it an end of chapter one or a full one, don't just answer the questions, go back in to the text and look up that area and find the answer, even if you know it.