You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you?

USER: I am Jerry Garcia. Due to my health problem I want to change my reservation, can you please help me to change my reservation?

ASSISTANT: Sure, please wait a moment. Sorry, there is no reservation with your name to cancel.

USER: That's fine. Thank you for your service.

ASSISTANT: Thanks for contacting us.