You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: I want to change my existing reservation due to sudden postpone of my family trip dates. Can you help me with that?

ASSISTANT: Sure, I can assist you with that one. Can I know your name please?

USER: I am Angela Collins.

ASSISTANT: Thank you for your information, I have checked with your information in my portal to change your booking but is displayed that there is no user name found to change it.

USER: Ok, no problem. Thank you.

ASSISTANT: You are most welcome and thank you for reaching us.