You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: I am Dennis Roberts.

ASSISTANT: Nice to meet you.

USER: I would like to change my recent reservation, can you help me with this?

ASSISTANT: Sure, please wait for a while. Sorry Roberts, there is no reservation found with your name in our records.

USER: That's fine, thanks for your help.

ASSISTANT: Most welcome.