You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you ?

USER: I am Helen Roberts, want to alter my recent reservation. Please help me out with that.

ASSISTANT: Sure, please give me a minute.

USER: Ok, take your time.

ASSISTANT: Sorry Helen, there is no reservation available on your name.

USER: It's ok, no issue. Thank you for your help.

ASSISTANT: You are welcome.