Hi KumarS,
First off, a 650/Q48 is a good score (it's right around the 80th percentile overall), so calling it "dismal" is not correct - and it might actually be enough to get you into Business School.
You mentioned your prior CAT scores, so I have some questions about those:
1) Did you take the ENTIRE CAT every time (including the Essay and IR sections)?
2) Did you take any of these CATs more than once?
3) What time of day did you take your CATs and what time of day was your Official GMAT?
4) What were the Quant and Verbal Scaled Scores on each of these CATs?
5) How did you sleep the night before your GMAT?
6) How long was the ride to the Testing Center from your home?
GMAT assassins aren't born, they're made,
Rich