You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I assist you?

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

ASSISTANT: Sure, could you please share your departure and arrival day?

USER: Can you please check the reservation with the name of Andrew Campbell?

ASSISTANT: Sure, please allow me a moment.

USER: Sure.

ASSISTANT: Sorry, there is no reservation with your name in our portal to make changes further.

USER: Not a problem, thank you for checking.

ASSISTANT: You are welcome, have a great day.