We booked transportation arrangements thru Rome Shuttle after seeing some good reviews of their services on this forum.

Yesterday they contacted me via email to confirm that they had a driver available for the date/time that we're arriving and asked that I email them our cell phone #, just in case there's an issue finding us at the airport.

However, they didn't ask for any credit card info for the 35 Euro transportation fee.

Is this customary? If you've used their services before do you just pay the day they transport you?