You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I be of your service?

USER: I need to change my recent reservation. Please help me in that.

ASSISTANT: Sure, I'll help you in changing an existing reservation. Can I know your name to check the reservation details?

USER: I am Gregory Walker.

ASSISTANT: Ok, give me some time.

USER: Ok.

ASSISTANT: Thank you for waiting, I have checked in reservation list to change your ticket, but could not find any reservation with your name.

USER: No problem, thanks for your information.

ASSISTANT: Thank you for approaching us.