You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello. How can I assist you?

USER: My name is Brenda Davis and I want to change an existing reservation. Please do help me with this.

ASSISTANT: OK, Brenda Davis, Please wait for a moment.

USER: OK, Sure.

ASSISTANT: Sorry, There is no reservation found on your  specified name.

USER: OK, Thank you.

ASSISTANT: Thanks for contacting us.