Hi Ashley ,
I hate to be the bearer of bad news , but with the scores you have it is not possible to get into a High Level B-School , Canadian or otherwise.
Given the poor perform across three attempts , consider other career choices more suited to your aptitude.
One cannot increase , substantially , his or her GRE Score. Any improvements in the score tend to fade away within one year , making it look as if there never was any improvement to begin with.
Before you begin to prepare for any exam make sure you "capable" of handling the job , should you clear the exam.
Once you have determined your ability , collect the adequate learning material , study the same , take mocks , correct your weakness , repeat the this process as many times as...