You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: I am Andrew Campbell, I just wanted to change my reservation due to my vacation trip got postponed. Will you please help me with that?

ASSISTANT: Sure, wait for a minute.

USER: Ok, please take a time.

ASSISTANT: Sorry Campbell, no reservation found on your name.

USER: Oh! It's ok fine, may be I did a mistake.

ASSISTANT: OK, thank you for approaching  us.

USER: Thank you for your help.