My Eurotunnel account bookings
If you made the booking yourself, it's likely you made the booking using your My Eurotunnel account. To access your booking you need to log in with your email address and a password you specified when you created your account. If you can't remember your password you can reset your password.
Standalone (one-off "guest" bookings)
If you booked via a travel agent, tour operator, or coach operator, you will need to contact them to request any changes to your booking