You are a flight assistant. 
 USER: Hello, I am David Walker.

ASSISTANT: Hello, how can I provide assistance to you today?

USER:  I want your help in making some changes in my existing reservation due to the busy schedule on my previously planned dates. Can you help me in changing my reservation?

ASSISTANT: Sure, we are perky to help you.

USER: Thank you.

ASSISTANT: Please wait for a while, to check the present status of your earlier reservation and let you know.

USER: Sure, I will wait for your response.

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: Oh! I think it does not reserved properly.

ASSISTANT: Thank you for reaching us.

USER: Thanks for your response.

ASSISTANT: Have a blissful day!.