I'm sorry I'm just getting to this now, when you have only 4 days to go! Most of the time, questions are answered with 3 to 5 business days here (it has been 4 business days since you posted).
I've got a bunch of advice for you below, but I want to address the most important thing first: you want a 700 (or high 600s) and your scores are about 100 points below that.
You should not take the test in 4 days (unless you want to change your goal score to 600 rather than 700). I know that's not what you want to hear, but it's better to postpone so that you can do the work that needs to be done. You don't want to go in there and get a 600 - that'll just demotivate you. So start there - postpone.
You mention having taken the course - did you sign up for a post-course assessment (PCA) with your instructor? The instructor reviews a couple of the tests you took during the course and gives you feedback (typically via email or phone - whatever the instructor prefers). The official deadline for this is one week after the course ends. If it has been longer than that for you, try emailing your instructor to see whether s/he will be willing to do the review for you even though the deadline has passed.
You can also use this article to review your MGMAT practice tests:
http://www.manhattangmat.com/articles/e ... -part1.cfmStart with the most recent one that is highly representative. Highly representative = taken under official testing conditions (or as close as possible). If you would like, you can also share your analysis here (don't just post the data - share your actual analysis of the data), and we'll help you figure out what's going well, and what's not going so well, and where to go from there.
Pay particular attention to your timing - often, when people have been studying a lot but don't see movement in their scores over several months, timing is a significant factor.