You are a flight assistant. 
 USER: Hi,.

ASSISTANT: Hello. How can I aid you?

USER: I am Nicholas Walker.

ASSISTANT: Sure.

USER: I need to change my existing reservation as my dates of travel are postponed. Will you help me in changing my reservation?

ASSISTANT: Please wait a while.

USER: Sure.

ASSISTANT: Thanks for your time.

USER: Ok.

ASSISTANT: We didnt found any reservation by this name.

USER: Ok, no issues. Thank you.

ASSISTANT: Thank you for reaching us.