You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you?

USER: I heard that your agency deals in amending of existing reservation. Is that correct?

ASSISTANT: Yes, what you heard about our agency is absolutely correct. Would you like me to change your existing reservation?

USER: That's good to hear from you. Actually, my brother has reserved a ticket to Philadelphia from Dallas. Due to his ill health, he is planning to postpone his trip, can you please help me in changing the existing reservation?

ASSISTANT: Sure, may I know your brother's name to check the reservation status?

USER: He has reserved the ticket with the name Andrew Campbell.

ASSISTANT: Please wait for a minute.

USER: Sure, I will wait for your response.

ASSISTANT: There is no active reservation found with your brother details.

USER: Oh! It seems like he might have changed the reservation already.

ASSISTANT: May be some times it happens.

USER: Thank you for your response.

ASSISTANT: Thank you for contacting us, hope you visit us again.