You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I help you?

USER: I am Justin Adams. I want to change my reservation due to health problem, can you help me?

ASSISTANT: Sure, please hold on for a moment to check your details.

USER: Sure, I will wait for your response.

ASSISTANT: Sorry to say, no reservation found on your name.

USER: No problem, thanks for checking.

ASSISTANT: Welcome.