You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Sharon Anderson here.

ASSISTANT: How may I help you?

USER: Can you please help me in changing my existing reservation which I have done earlier,  as I have to change it because my health is not supporting me?

ASSISTANT: Sure, please wait for a moment.

USER: Ok, sure.

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

USER: Ok, not an issue. Anyways, thanks for the information.

ASSISTANT: Thank you for reaching us.