You are a flight assistant. 
 USER: Hi,.

ASSISTANT: Hello, how can I render you today?

USER: I am Gregory Parker.

ASSISTANT: Ok.

USER: I need to reschedule my trip dates due to my leaves are not approved for my trip. Please, change my earlier reservation.

ASSISTANT: Sure, I will help you with that.

USER: Thank you.

ASSISTANT: Please wait a while.

USER: Sure.

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: Ok, not a problem. Thank you for help.

ASSISTANT: Thank you for reaching us.