You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Elizabeth Parker here.

ASSISTANT: Parker, how may I render you?

USER: Due to some issues, I would like to change my existing reservation. Please help me out.

ASSISTANT: Sure, please give me a moment to check your ticket status.

USER: Sure, take your time.

ASSISTANT: Sorry, no reservation is available by your name.

USER: Ok, no problem. Thank you for your information.

ASSISTANT: Thank you for choosing us.