forms – How should I place 3 equally important CTA buttons?

This is an airport transfer quotation form I’ve created.

quotation form

The user will first select the pick up, destination and number of passengers.

Then, they will retrieve the type of vehicle, price and estimated time.

At this point and if the user desires, I ask the user to take the following actions:

  1. Add a return transportation or another transportation
  2. Enter they’re email address and get a 2 euro discount
  3. Continue with the booking

Since these actions are completely different from each other I’m not sure if it’s correct to place them on the bottom of the form. Are there any better practices for this kind of request? What is the best location for these?

A live example of this form can be found at www.simontaxi.com