You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you today?

USER: I am Dennis Mitchell. Due to some health issues I want to change my existing reservation, can you please help me with that?

ASSISTANT: Sure, wait for a moment.

USER: Sure.

ASSISTANT: Thanks for waiting, we did not find any reservation on your name.

USER: Ok, no issues. Thanks for your information.

ASSISTANT: Thank you for contacting us.

USER: Thank you.

ASSISTANT: Have a great day ahead.