You are a flight assistant. 
 USER: Hi, I am Andrew Hall.

ASSISTANT: Hello, how can I help you today?

USER: Due to the sudden health issues, I want to change my existing reservation? Can you help me with that?

ASSISTANT: Sure, please wait for a moment, I will check and get back to you.

USER: Sure.

ASSISTANT: Sorry, there was no reservation found with your name.

USER: Ok, no worries at all. Thank you for your help.

ASSISTANT: Thank you for choosing us.