Dear Vasant, just tell me how this arrangement is different from some security agency? For a security agency to perform their operations, you provide them facilities like furniture, shades for the security guards, lockers to change their dress, etc. Security personnel come, do their duties, and go back. For providing these services, if you check their bill, you will find the component of PF/ESI too.
Therefore, in your case as the owner of the drivers' agency, you should include PF/ESI in the bill itself. To be on the safer side, it is better to mention the PF/ESI component against each individual too. Secondly, ask the agency to provide a xerox copy of the monthly return also.
For Sebastian KS: You have written that "It is better to have a service contract with the bus owner. Thus, you don't need to employ a driver. What you want is that your employees are picked on the dates specified. Since you don't give salary to the driver, you don't need to pay PF/ESI. But the payment you are giving to the bus owner, you may have to give service tax."
In the above case, you need to pay ESI. If the labor component is not mentioned in the service contract, then you have to assume 40% of the contract amount is a labor charge and pay the ESI monthly. The onus for payment is on the principal employer in such cases.
Regards, DVD