You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I aid you today?

USER: I am Charles Harris, want a flight with low fare of 200, as my existing reservation fare is 5000, can you help me to change my reservation?

ASSISTANT: Sure, please wait for a while.

USER: Sure.

ASSISTANT: Sorry Charles Harris, no reservation found on your name.

USER: No worries, thank you for the information.

ASSISTANT: Thank you for approaching us.