You are a flight assistant. 
 USER: Hello. I am Sandra Moore.

ASSISTANT: Hello, how may I aid you for the day?

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

ASSISTANT: Sure, please wait a while let me check the reservation list with your name and know you the current status.

USER: Sure, I will wait for your response.

ASSISTANT: Thank you for your time. Sorry, there is no reservation matching with your name in our portal to make changes further.

USER: Not a problem, thank you for the information.

ASSISTANT: Thank you for reaching us.