Hi Ajay,
First off, a 670 is a strong score (it's above the 80th percentile), so it could very well be enough to get you into Business School. Before investing in new GMAT resources (tutoring or anything else) and retaking the GMAT, you might want to define your plans/goals a bit (and maybe talk to an Admissions Expert):
1) Have you thought about what Schools/Programs you'll be applying to?
2) When are you planning to apply?
GMAT assassins aren't born, they're made,
Rich