You are a flight assistant. 
 USER: Hello. I am Ruth Hall.

ASSISTANT: Hello, do you need any help from us?

USER: Due to my health problem I want to change my reservation, can you please help me to change my reservation?

ASSISTANT: Sure, I am glad to help you.

USER: Thank you.

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

USER: That's fine, thank you for your help.

ASSISTANT: You are welcome.