You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I assist you today?

USER: I would like to spend some more days with my mother, please help me in changing my existing reservation.

ASSISTANT: Sure, I will help you with that.

USER: Thank you.

ASSISTANT: Let me know your name to check your reservation?

USER: My name is Patrick Williams.

ASSISTANT: Ok, please wait a while.

USER: Sure, take your time.

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, no problem. Thank you for your information.

ASSISTANT: Thank you for choosing us.