Why do you need a tour operator? India is very "user friendly" - a few 'phone calls and a bit of improvisation (hire a car and driver, or work out the local Volvo schedules). I visited India 13 times in the space of 4 years, never needed any help from anyone.
There are various tour operators in Mumbai which provide best in class services. Simons Holidays is among one of them. They provide wide variety of packages to its patrons.