You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I guide you for today?

USER: Owing to an emergency, my planned trip to Yosemite adventure got postponed. So I request you to alter my existing reservation.

ASSISTANT: I am here to help you with that. Could you please provide your name to check the active reservation?

USER: Sure, I have a existing reservation with name Amanda Brown.

ASSISTANT: I regret to say this, I have not found any active reservation with such a name to alter your reservation.

USER: Ok, no worries at all. I appreciate your kind service.

ASSISTANT: You are welcome, thank you for reaching our service.