You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you?

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

ASSISTANT: Please wait for a moment.

USER: Sure. I will wait.

ASSISTANT: Sorry, there is no reservation found basis on your details.

USER: That's fine. Thank you for your help.

ASSISTANT: Most welcome.