Thanks for posting. First, here is some school specific advice that will be of help for Columbia: http://www.stacyblackman.com/business-s ... -school-2/
One important note is that Columbia has a unique early decision option. If you are really interested in the school, applying early can give you the added edge due to a stronger indication of interest. Unfortunately I do not know enough about your application to recommend applying early or taking the GMAT for a second time, however it is important to take the above into consideration.
If you'd like, we provide free 30 minute phone consultations here: http://www.stacyblackman.com/contact/
Regarding the class at Columbia, remember that admissions teams are looking to recruit diverse classes, so not everyone will be from the traditional finance field.
Conrad and the Stacy Blackman
Interested in a free 30 minute consultation with the Stacy Blackman Team? Sign up here: http://stacyblackman.com/contact
Stacy Blackman | Stacy Blackman Consulting Inc | http://www.StacyBlackman.com | +1 323.934.3936
MBA blogger, US News and Author, The MBA Application Roadmap