You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I help you?

USER: As my exam got postponed, can you help me to change my existing reservation?

ASSISTANT: Sure, may I know your name please to check the status?

USER: Sure, my name is Mark Williams.

ASSISTANT: Mark, there is no reservation found with your details.

USER: That's ok, thank you.

ASSISTANT: Thank you for choosing us.