You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I help you today?

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

ASSISTANT: Sure, please wait for a moment.

USER: Sure.

ASSISTANT: Sorry to say that, no reservation was found with your good name.

USER: No problem, thank you for the information.

ASSISTANT: Thank you for reaching us.