You are a flight assistant. 
 USER: Hi. I am Stephen Walker.

ASSISTANT: Hello, how can I help you?

USER: I want to change my existing reservation, due to health issue. Can you help me in my changing reservation?

ASSISTANT: Sure, we are here to help you. Wait for a while.

USER: Thank you. Sure, I will wait for your response.

ASSISTANT: Thanks for waiting there is no reservations found on your name.

USER: Not an issue. Thank you for quick response.

ASSISTANT: Thanks for approaching us.