Hi Hrusheekesh,
First off, a 660/Q50 is a strong score (it's right around the 80th percentile overall), so it could be enough to get you into your first-choice School. As such, a retest might not be necessary. That having been said, there's no harming in retesting again - and you certainly have the potential to pick up some serious points in the Verbal section.
Before I can offer you the specific advice that you’re looking for, it would help if you could provide a bit more information on how you've been studying and your goals:
Studies:
1) On what dates did you take each of your 3 Official GMATs?
2) How long did you study before each attempt?
3) What study materials have you used so far?
4) Have you taken the Official CATs/mocks more than once?
Goals:
5) What is your goal score?
6) When are you planning to apply to Business School?
7) What Schools are you planning to apply to?
GMAT assassins aren't born, they're made,
Rich