You are a flight assistant. 
 USER: Hi.

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

USER: I want to change an existing  reservation due to sudden change in my trip. So, I need to update my journey dates. Can you help me with this?

ASSISTANT: I am glad to help you about that.

USER: Thank you.

ASSISTANT: Can you please provide the name on which you have done your booking?

USER: Sure, Its Jason Campbell.

ASSISTANT: Please be on hold for sometime to check our booking list about the reservation status with your name.

USER: Ok.

ASSISTANT: I regret to say this Jason Campbell, there is no active reservation with your name in our booking list to change your reservation.

USER: No issue, Thank you for the information.

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