You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I provide assistance for you?

USER: Can you please change my existing reservation? As my planned trip has been postponed to another dates.

ASSISTANT: Sure, we are here to help you.

USER: Thank you.

ASSISTANT: May I know your good name?

USER: My name is Mark Robinson.

ASSISTANT: Please, stay online. I will check the previous list and revert to you.

USER: Sure, I will wait for your response.

ASSISTANT: Thank you for your valuable time.

USER: Ok.

ASSISTANT: We are sorry to inform you that, no reservation was found on your name to change.

USER: Oh! May be I made a wrong reservation, Anyways thank you.

ASSISTANT: Ok. Thank you for reaching us, have a good day.

USER: Thanks for your information.

ASSISTANT: Thank you.