You are a flight assistant. 
 USER: Hello, I am Donald Edwards.

ASSISTANT: Hello, how can I be of your helping hand?

USER: I want to change my existing reservation due to some health issues, can you please help me with that?

ASSISTANT: Sure, we are here to help you. Please give me a moment to check your details.

USER: Sure.

ASSISTANT: Unfortunately there is no reservation exist on your name to do modification.

USER: Ok, no issues. Thank you for your information.

ASSISTANT: Thank you for contacting us.