Neighborhood Travel Agency/Drivers having contacts with the MNC transportation head/concern.
Its absolutely rely upon how the inner contacts are solid.
They may be useful.
Broadly put, there are two ways to do this. There are agencies that are usually looking for more cars. They are the ones who will take you car, do the required servicing and provide their own drivers. Of course, you would get comparatively less return.
Then there are companies who would attach their name to your car. But you have to provide your own driver and bear the expense of servicing.
So, see which one of these options fit your needs and preferences better. The easiest way to start in this process is do some online search. You can find such agency/company easily. Or you can go and directly talk to drivers and people who have their car attached to some company. They could explain things to you much more clearly. On the other hand, you can also directly approach companies/agencies. Just visit their office and talk to them.