Generally there are two variants GMAT tutorship.
I guess the best prep classroom courses in the Bangalore would be to reach out Crack Verbal by Arun.
The other is to take up online courses like E-gmat, Dominate The Gmat where you can interact with the teachers over a webcast. Or The courses like Manhattan GMAT, Kaplan, Grockit etc. where the course is self prep and no tutorship is available.