First off, the price is gigantic just for the option to 'prepay'. It is the same taxi service that is already at the airport, which is substantially less. Additionally, I was emailed by a driver asking for an additional fee. On top of that, I had to make a change because of a flight delay and they asked for additional fees. Save yourself the complete headache and book the taxi at the airport. The cabs are the same. I do no recommend this service.