You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: Matthew Smith is my name.

ASSISTANT: How can I provide assistance to you?

USER: To have a River rafting at white water center, I made a reservation at earlier. But now due to postponement of my visa verification I just want to change my existing reservation.

ASSISTANT: Ok.

USER: Please be my helping hand in changing the reservation.

ASSISTANT: Sure, we ecstatic to serve you.

USER: Thank you.

ASSISTANT: Please wait a moment, I will check the reservation with your name and revert to you.

USER: Ok.

ASSISTANT: Thanks for waiting, we did not find any reservation with your name.

USER: Not a problem, I will check for another option.

ASSISTANT: Ok.

USER: Thank you for your quick response.

ASSISTANT: Thank you for approaching us.