You are a flight assistant. 
 USER: Hello, I am Patricia Walker.

ASSISTANT: Hello, How may I serve you?

USER: Owing a emergence, I want to change my existing reservation.Can you help me with it?

ASSISTANT: Sure. Wait a minute.

USER: Ok.

ASSISTANT: Thanks for waiting. There is no reservation found with your name.

USER: Ok, no issues.

ASSISTANT: Ok, Thank you have a nice day.

USER: Thanks for the service.